Paid Family Leave and Prevention of Acute Respiratory Infections in Young Infants

Katherine A Ahrens; Teresa Janevic; Erin C Strumpf; Arijit Nandi; Justin R Ortiz; Jennifer A Hutcheon

doi:10.1001/jamapediatrics.2024.3184

. 2024 Aug 26:e243184. Online ahead of print. doi: 10.1001/jamapediatrics.2024.3184

Paid Family Leave and Prevention of Acute Respiratory Infections in Young Infants

Katherine A Ahrens ^1,^✉, Teresa Janevic ², Erin C Strumpf ³, Arijit Nandi ⁴, Justin R Ortiz ⁵, Jennifer A Hutcheon ⁶

¹Muskie School of Public Service, University of Southern Maine, Portland, Maine

²Department of Epidemiology, Columbia University Mailman School of Public Health, New York, New York

³Department of Economics and Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Québec, Canada

⁴Department of Equity, Ethics, and Policy and Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Québec, Canada

⁵Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland

⁶Department of Obstetrics & Gynaecology, University of British Columbia, Vancouver, British Columbia, Canada

Accepted for Publication: May 26, 2024.

Published Online: August 26, 2024. doi:10.1001/jamapediatrics.2024.3184

^✉

Corresponding Author: Katherine A. Ahrens, PhD, MPH, University of Southern Maine, 34 Bedford St, Portland, ME 04101 (katherine.ahrens@maine.edu).

Author Contributions: Dr Ahrens had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: All authors.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Ahrens, Ortiz, Hutcheon.

Critical review of the manuscript for important intellectual content: Ahrens, Janevic, Strumpf, Nandi, Ortiz.

Statistical analysis: All authors.

Obtained funding: Ahrens, Strumpf, Hutcheon.

Administrative, technical, or material support: Ahrens, Ortiz.

Conflict of Interest Disclosures: Dr Ahrens reported grants from the National Institute of Child Health and Human Development during the conduct of the study. Dr Janevic reported grants from the National Institute of Child Health and Human Development during the conduct of the study. Dr Strumpf reported grants from the National Institutes of Health during the conduct of the study. Dr Ortiz reported grants from the National Institutes of Health during the conduct of the study and personal fees from Moderna, Pfizer, and GSK outside the submitted work. Dr Hutcheon reported grants from the National Institutes of Health and grants from Federal Government of Canada during the conduct of the study. No other disclosures were reported.

Funding/Support: Research reported in this publication was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health (R03HD108526).

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This publication was produced from raw data purchased from or provided by the New York State Department of Health. However, the conclusions derived, and views expressed herein are those of the author(s) and do not reflect the conclusions or views of New York State Department of Health. The New York State Department of Health, its employees, officers, and agents make no representation, warranty or guarantee as to the accuracy, completeness, currency, or suitability of the information provided here. The analyses, conclusions, and recommendations drawn from Vermont Uniform Hospital Discharge Data System are solely those of the study authors and are not necessarily those of the Green Mountain Care Board. The analyses, conclusions, interpretations, and recommendations drawn from the Confidential Data are solely those of the study authors and not necessarily those of the New Hampshire Department of Health and Human Services.

Meeting Presentation: This paper was presented at the annual meeting of the Society for Epidemiologic Research; June 20, 2024; Austin, Texas and at the annual meeting of the American Society for Health Economists; June 17, 2024; San Diego, California.

Data Sharing Statement: See Supplement 2.

Additional Contributions: We thank Megan Bardsley, MSc, and colleagues from the Field Services South West, Health Protection Operation UK Health Security Agency, London, United Kingdom, for sharing details of the analytic approach and statistical code used by their team from related work.

^✉

Corresponding author.

PMCID: PMC11348083 PMID: 39186259

This study attempts to determine if the 2018 introduction of paid family leave in New York State reduced acute care encounters for respiratory tract infections in infants 8 weeks old or younger.

Key Points

Question

Did acute care encounters for respiratory tract infections decrease in infants 8 weeks old or younger after New York state introduced paid family leave in 2018?

Findings

This controlled time series analysis found that acute care encounters for respiratory tract infections were 18% lower after the introduction of paid family leave than in the absence of the policy.

Meaning

These findings provide evidence that a state paid family leave policy may reduce acute care encounters for respiratory tract infections in young infants.

Abstract

Importance

Acute respiratory tract infections are the leading cause of emergency department visits and hospitalizations in US children, with highest risks in the first 2 months after birth. Out-of-home childcare settings increase the spread of respiratory tract infections. The study team hypothesized that access to state-paid family leave could reduce acute care encounters (hospital admissions or emergency department visits) for respiratory tract infections in young infants by reducing out-of-home childcare transmissions.

Objective

To determine if the 2018 introduction of paid family leave in New York state reduced acute care encounters for respiratory tract infections in infants 8 weeks or younger.

Design, Setting, and Participants

This population-based study of acute care encounters took place in New York state and New England control states (Maine, Massachusetts, New Hampshire, Vermont) from October 2015 through February 2020. Participants included infants aged 8 weeks or younger. Controlled time series analysis using Poisson regression was used to estimate the impact of paid family leave on acute care encounters for respiratory tract infections, comparing observed counts during respiratory virus season (October through March) with those predicted in the absence of the policy. Acute care encounters for respiratory tract infections in 1-year-olds (who would not be expected to benefit as directly from the policy) were modeled as a placebo test.

Intervention

New York State Paid Family Leave policy, introduced on January 1, 2018, providing 8 weeks of paid leave for eligible parents.

Main Outcomes and Measures

Emergency department visits or hospitalizations with International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (ICD) codes for upper or lower respiratory tract infections or associated symptoms (ie, fever, cough), excluding newborn hospitalizations. The secondary outcome was acute care encounters for respiratory syncytial virus (RSV) bronchiolitis.

Results

There were 52 943 acute care encounters for respiratory infection among infants 8 weeks or younger. There were 15 932 encounters that were hospitalizations (30%) and 33 304 of the encounters were paid for by Medicaid (63%). Encounters were 18% lower than predicted (relative percentage change = −17.9; 95% CI, −20.3 to −15.7) after the introduction of paid family leave. RSV encounters were 27.0% lower (95% CI, −30.9 to −23.5) than predicted. Similar reductions were not observed in 1-year-olds (relative percentage change = −1.5; 95% CI, −2.5 to −0.6).

Conclusions

New York state’s paid family leave policy was associated with reduced acute care encounters for respiratory tract infections in young infants. These findings may be useful for informing implementation of paid family leave federally and in the states that have not enacted paid family leave policies.

Introduction

Acute respiratory tract infections are the leading cause of hospitalization in US children younger than 5 years and the most common reason why children present to an emergency department (ED). The first months after birth are highest risk. Hospitalizations for lower respiratory tract infection among infants 2 months or younger are twice as high as among 3- to 5-month-olds (17.9 vs 8.0 per 1000, respectively) and 4.5 times as high as among 6- to 11-month-olds (3.9 per 1000).

Young infants commonly acquire respiratory tract infections in the daycare setting. Out-of-home care has consistently been associated with 2- to 3-times higher risk of infection compared with in-home care. The risk associated with out-of-home childcare is most pronounced in the youngest infants. In the US, infants begin out-of-home care at very young ages due to the lack of paid family leave. Approximately half of employed US women have no paid family leave and an additional 25% have less than 6 weeks paid leave. One study found 1 in 4 employed women in the US return to work within 2 weeks of giving birth and nearly half return to work by 6 weeks. State-paid family leave increases the amount of time that new parents engage in childcare, delaying the start of out-of-home childcare. Thus, providing parents with paid family leave increases the chances that young infants will be cared for at home during the time they are most vulnerable to acquiring respiratory tract infections. In addition, paid family leave can increase breastfeeding rates and pediatric visit attendance, which may also reduce the risk of acquiring respiratory tract infections.

On January 1, 2018, New York state became the fourth state in the nation to introduce paid family leave (after California, Rhode Island, and New Jersey). At the time of its introduction, New York’s policy was the most comprehensive in the nation, being the first to provide 8 weeks of parental leave, have no waiting period, and include job and discrimination protection to all eligible employees in the state. In its first year, parental leave was claimed for approximately one-third of infants born in New York state, the highest uptake among states with paid leave and the percentage of working mothers taking paid family leave increased from 55% to 70%.

The objective of this study was to evaluate whether New York state’s paid family leave policy reduced acute care encounters (ED visits or hospitalization) for respiratory tract infection in infants 8 weeks or younger compared with regional control states (Maine, Massachusetts, New Hampshire, Vermont). As a secondary aim, we evaluated whether the policy reduced acute care encounters for respiratory syncytial virus (RSV) bronchiolitis in infants 8 weeks or younger, as RSV bronchiolitis is the most common type of respiratory tract infection in infants.

Methods

Hypothesis

We hypothesized that provision of paid family leave could reduce respiratory tract infections in young infants that are commonly acquired through out-of-home childcare.

Data

We obtained all records of hospitalizations and ED visits that did not result in hospitalizations from New York, Maine, Massachusetts, New Hampshire, and Vermont. All records contained encounter-level information on patient characteristics (including age, race and ethnicity, and expected payer), diagnoses, and health care services. All datasets are available through a data use agreement with individual agencies. We selected control states geographically proximal to New York state within the Northeast region of the US but did not include states with paid family leave policies during the study period (New Jersey, Rhode Island), lacking statewide ED and hospitalization data (Pennsylvania), or with a high proportion of residents who commuted to New York state for work (Connecticut), who were eligible for the policy.

Our study period included acute care encounters from October 1, 2015, through February 29, 2020. Our start date coincided with the International Classification of Diseases Clinical Modification (ICD-CM) coding switch from version 9 to 10 in the US, ensuring a consistent coding system throughout our study period. Our end date was shortly before the COVID-19 pandemic, which affected health care use and disrupted normal patterns of respiratory infectious diseases transmission. The study was approved by University of Southern Maine’s institutional review board (22-06-1874). We followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines for cohort studies.

Paid Family Leave Policy in New York State

On January 1, 2018, New York state introduced a paid family leave policy providing most private and certain public employees who work in New York state with up to 8 weeks of job-protected paid leave that can be taken within the first 12 months of their child’s birth. Benefits of the policy were phased in over 4 years, increasing to 12 weeks of paid leave in January 2021; however, for the purpose of consistency within the study period, we restricted our focus to the first 8 weeks after birth.

Primary Outcome: Acute Care Encounters for Respiratory Tract Infection

We identified upper or lower acute respiratory tract infection hospitalizations and ED visits among infants aged 56 days (8 weeks) or younger using ICD-10 diagnosis codes (eTable 1 in Supplement 1). We included acute care encounters with codes (in any position) for upper (J00-J06) and lower (J09-J18, J20-J22) respiratory tract infections, otitis media (H65-H67), and whooping cough (A37), as well as common respiratory tract symptoms (cough [R05] and fever [R502, R5081-R5084, R509]). We excluded acute care encounters for birth hospitalizations.

Secondary Outcome: Acute Care Encounters for RSV

Our secondary outcome was acute care encounters for RSV bronchiolitis (ICD-10 code J21.0), which was a subset of the primary study outcome.

Additional Study Outcomes

We additionally examined the following outcomes: upper respiratory tract infections acute care encounters, lower respiratory tract infection acute care encounters, and respiratory tract infection-related hospitalizations only. These were also subsets of the primary study outcome (eTable 1 in Supplement 1).

Denominator

Our denominator was the number of infants 8 weeks or younger living each month in each state, ie, born in the current or prior month based on state-level hospitalization records for live birth deliveries.

Statistical Analysis

We visualized temporal trends in respiratory tract infection–related and RSV-related acute care encounters for infants 8 weeks or younger for each state. We used descriptive statistics to examine characteristics of deliveries and respiratory tract infection–related acute care encounters throughout the study period. We plotted changes in study population characteristics over time to ensure that there were no abrupt changes in characteristics coinciding with the introduction of the new family leave policy.

We used controlled time series analysis to estimate the impact of introducing paid family leave on each of our study outcomes. We used a time series approach rather than other approaches commonly used in policy evaluations, such as difference-in-differences, because a time series approach best captures the highly seasonal patterns of respiratory tract infections. We built a Poisson regression model estimating time trends in the monthly count of acute care encounters using data from the prepolicy period (before January 1, 2018) in New York state and all years for control states, with an indicator variable to specify rates in New York state vs control states. We originally intended to use negative binomial regression but switched to Poisson regression when some of these models failed to converge. Estimates from the models that did converge were the same as from Poisson regression models. We accounted for the strong seasonality of respiratory tract infections using indicator variables for calendar month, which provided a better fit than the use of harmonic functions (sine and cosine). We accounted for year-to-year variation in severity of respiratory virus seasons by creating a term that expressed the cumulative burden (count) of the outcome in a given season (October through March) as the relative difference compared with the cumulative burden during the first season in our study period (October 2015 through March 2016) using data from control states only. Models were offset by the estimated number of infants aged 8 weeks or younger in a given month. We used robust standard errors to account for residual autocorrelation of error terms among consecutive observations. See the eAppendix in Supplement 1 for further details of our model and statistical code.

We used this model to predict the expected monthly counts of acute care encounters for our study outcomes in the absence of the policy in New York state for each month of the postpolicy period. We summed predicted counts for each postpolicy respiratory virus season or portion thereof (January through March 2018, October 2018 through March 2019, October 2019 through the end of the study period [February 2020]), and across all respiratory virus seasons postpolicy (January 2018 to February 2020). These estimates represented the counterfactual scenario of the number of acute care encounters that we would expect to observe if paid family leave had not been implemented in New York state. We calculated absolute differences and relative percentage change between the actual observed counts in each of the postpolicy respiratory virus seasons compared with the counterfactual predicted counts with 95% CIs calculated through bootstrap resampling (1000 iterations). As not all eligible families used paid family leave and eligibility status was not available in our dataset, our study estimates are analogous to intention-to-treat effects, reflecting the overall impact of the program as implemented in practice.

Placebo Test

We conducted a placebo test (ie, a negative control) to help rule out the possibility that our primary effect was caused by a factor other than the introduction of paid family leave (eg, a health care reform that decreased ED encounter rates). We repeated our analyses in a population that should not have been as directly affected as young infants by paid family leave: 1-year-old infants. Any observed association in this population would be interpreted as evidence of residual confounding in our primary analysis. We selected 1-year-olds (12 months to younger than 24 months) because their parents were no longer eligible to take paid parental leave (unless they were adopted) and they were also less likely to be indirect beneficiaries of paid family leave through the birth of a younger sibling compared with children older than 24 months (as 85% of interpregnancy intervals in the US are more than 12 months; ie, most siblings are more than 21 months apart in age).

Results

There were 950 020 deliveries in New York state and 426 342 deliveries in the control states between October 2015 and February 2020. Before the introduction of paid family leave, deliveries in New York state were more likely to be paid for by Medicaid than in control states (44.5% vs 36.2%) and were less likely to be among non-Hispanic White women (45.7% vs 66.5%), while maternal age and preterm birth rates were similar (eTable 2 in Supplement 1). Despite these differences, characteristics were relatively stable throughout the study period within each group.

Acute Care Encounters for Respiratory Tract Infection

There were 52 943 acute care encounters (hospitalization or ED visits) in infants 8 weeks or younger for respiratory tract infection and related symptoms in New York and control states. Of these, approximately 30% were hospitalizations with a median length of stay of 2 days (Table 1). Most acute care encounters were paid for by Medicaid (63%).

Table 1. Characteristics of Acute Care Encounters (Hospitalization and Emergency Department Visits) in Infants 8 Weeks or Younger for Respiratory Tract Infection and Related Symptoms in New York State as Compared With Control States, October 2015 through February 2020^a.

Encounter characteristic, treatment group	No. (%)
	Before paid family leave in New York state (October 1, 2015 to December 31, 2017)		After paid family leave in New York state (January 1, 2018 to February 29, 2020)
	New York	Control states^b	New York	Control states^b
No.	19 299 (100.0)	7910 (100.0)	17 289 (100.0)	8445 (100.0)
Encounter type
Emergency department visit	12 898 (66.8)	5805 (73.4)	12 070 (69.8)	6238 (73.9)
Hospitalization	6401 (33.2)	2105 (26.6)	5219 (30.2)	2207 (26.1)
Encounter year
2015 (Partial year)	2347 (12.2)	778 (9.8)	0 (0)	0 (0)
2016	8614 (44.6)	3402 (43.0)	0 (0)	0 (0)
2017	8338 (43.2)	3730 (47.2)	0 (0)	0 (0)
2018	0 (0)	0 (0)	7787 (45.0)	3591 (42.5)
2019	0 (0)	0 (0)	7600 (44.0)	3752 (44.4)
2020 (Partial year)	0 (0)	0 (0)	1902 (11.0)	1102 (13.1)
Race and ethnicity^c
Hispanic	4966 (25.7)	1560 (19.7)	4338 (25.1)	1693 (20.1)
Non-Hispanic Asian or Pacific Islander	1417 (7.3)	234 (3.0)	1245 (7.2)	220 (2.6)
Non-Hispanic Black	3321 (17.2)	709 (9.0)	2670 (15.4)	658 (7.8)
Non-Hispanic Native American	44 (0.2)	15 (0.2)	68 (0.4)	26 (0.3)
Non-Hispanic White	5933 (30.7)	4483 (56.7)	5811 (33.6)	4728 (56.0)
Missing	0 (0)	457 (5.8)	0 (0)	688 (8.2)
Other^d	3618 (18.8)	452 (5.7)	3157 (18.3)	432 (5.1)
Insurance, primary payer
Missing	13 (0.1)	0 (0)	6 (0)	3 (0)
Medicaid	12 809 (66.4)	4728 (59.8)	11 067 (64.0)	4700 (55.7)
Private insurance	5071 (26.3)	2697 (34.1)	5253 (30.4)	3056 (36.2)
Other	1406 (7.3)	485 (6.1)	963 (5.6)	686 (8.1)
Length of stay, d^e
Mean (SD)	4.4 ( 10.8)	6.6 (19.2)	4.2 (9.2)	6.4 (21.7)
Median (IQR)	2 (2-4)	2 (2-5)	2 (2-4)	3 (2-4)

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Abbreviation: IQR, interquartile range.

^{^a}

Data sources: New York State Statewide Planning and Research Cooperative System all-payer hospital claims records New York State Database from the Healthcare Cost and Utilization Project Agency for Healthcare Research and Quality; Maine Health Data Organization Inpatient and Outpatient Encounters; Massachusetts Center for Health Information and Analysis; New Hampshire Limited Use Uniform Healthcare Facility Discharge Data Set; Vermont Uniform Hospital Discharge Data Set.

^{^b}

Includes Maine, Massachusetts, New Hampshire, and Vermont.

^{^c}

It is unknown whether race and ethnicity were self-reported in these data sources.

^{^d}

Other race and ethnicity was not further defined in the data sources.

^{^e}

Hospitalizations only.

Figure 1 shows the crude rates of these acute care encounters per 1000 infants 8 weeks or younger by calendar month. As expected, strong seasonal patterns were present with rates approximately 3 to 4 times higher in the peak winter months than in summer months. In the 2015 to 2016 and 2016 to 2017 respiratory virus seasons (before the introduction of paid family leave), rates in New York state were similar to those of control states. However, after the introduction of paid family leave, rates in New York state were lower than those in control states that experienced more severe respiratory tract infection seasons after January 1, 2018, (ie, January through March 2018, 2018 to 2019, and 2019 to 2020) than in the seasons before.

Figure 2 shows the rates predicted by the model for New York state in the absence of a policy change with the observed rates. In line with the patterns experienced in control states, predicted rates were higher in the January through March 2018, 2018 to 2019, and 2019 to 2020 respiratory virus seasons than in the earlier years of our study period. The observed rates in New York state before the introduction of paid family leave were similar to the predicted rates (ie, the cumulative acute care encounters for respiratory tract infections were 0.3% higher [95% CI, −1.8% to 2.4%], corresponding to 35 more encounters), establishing that the model was well fitted to observed data prepolicy (eTable 3 in Supplement 1). In contrast, the observed rates in New York state after the introduction of paid family leave were significantly lower than predicted with cumulative counts of acute care encounters for respiratory tract infections 18% lower (95% CI, −20% to −16%) (Table 2). This corresponded to 2671 fewer encounters. The relative percent change varied across the postpolicy seasons, ranging from 9% lower in the 2019 to 2020 season to 27% lower from January through March 2018.

Table 2. Controlled Time Series Analysis of Acute Care Encounters in Infants 8 Weeks or Younger After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)^a.

Outcome	Observed monthly count	Estimated effect of paid family leave (vs no leave)
Outcome	Observed monthly count	Predicted monthly count (95% CI)	Difference in counts (95% CI)^b^,^c	Relative percentage change^d (95% CI)^c
Any respiratory tract infection or associated symptoms
Jan 2018 to Mar 2018	2535	3455 (3356-3567)	−920 (−1032 to −821)	−26.6 (−28.9 to −24.4)
Oct 2018 to Mar 2019	5008	6285 (6078-6498)	−1277 (−1490 to −1070)	−20.3 (−22.9 to −17.6)
Oct 2019 to Feb 2020	4722	5196 (4980-5409)	−474 (−687 to −258)	−9.1 (−12.7 to −5.2)
Total postpolicy	12 265	14 936 (14 543-15 380)	−2671 (−3115 to −2278)	−17.9 (−20.3 to −15.7)
RSV bronchiolitis
Jan 2018 to Mar 2018	845	1542 (1465-1631)	−697 (−786 to −620)	−45.2 (−48.2 to −42.3)
Oct 2018 to Mar 2019	1742	2489 (2371-2625)	−747 (−883 to −629)	−30.0 (−33.7 to −26.5)
Oct 2019 to Feb 2020	1932	2157 (2019-2315)	−225 (−383 to −87)	−10.4 (−16.6 to −4.3)
Total	4519	6188 (5903-6453)	−1669 (−1934 to −1384)	−27.0 (−30.9 to −23.5)

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Abbreviation: RSV, respiratory syncytial virus.

^{^a}

Data source: New York State Statewide Planning and Research Cooperative System all-payer hospital claims records; New York State Database from the Healthcare Cost and Utilization Project Agency for Healthcare Research and Quality; Maine Health Data Organization Inpatient and Outpatient Encounters; Massachusetts Center for Health Information and Analysis; New Hampshire Limited Use Uniform Healthcare Facility Discharge Data Set; Vermont Uniform Hospital Discharge Data Set.

^{^b}

Difference in counts = observed minus predicted.

^{^c}

Confidence intervals calculated by bootstrapping 1000 samples.

^{^d}

Relative percentage change = 100 × (difference in counts) / predicted.

Respiratory Syncytial Virus

Among the subset of 15 726 acute care encounters for RSV bronchiolitis, rates were approximately 15 to 20 times higher in the peak winter months than in summer months (Figure 1). Observed rates in New York state were similar to predicted rates in each season before the policy (eTable 3 in Supplement 1). In contrast, observed rates in New York state were significantly lower than predicted in the absence of paid family leave with cumulative counts of acute care encounters for RSV bronchiolitis 27% lower (95% CI, −31% to −24%) (Table 2). As with the primary outcome, the relative percentage change varied across the seasons, ranging from 10% lower in the 2019 to 2020 season to 45% lower from January to March 2018.

Other Study Outcomes

For the other subsets of respiratory tract infection–related outcomes that were examined (upper respiratory tract infection, lower respiratory tract infection, and any respiratory tract infection or associated symptoms [hospitalizations only]), the study team also found lower rates in New York state postpolicy than were predicted in the absence of the policy (eTable 4 in Supplement 1).

Placebo Test

In children aged 12 months to younger than 24 months, a population hypothesized to have unlikely been affected by paid family leave, the observed rates in respiratory tract infection–related acute care encounters were similar between New York and control states before and after the policy (eFigure 1 in Supplement 1). No clinically meaningful reduction was found postpolicy (−1.5% lower; 95% CI, −2.5% to −0.6%) (Table 3, eFigure 2 in Supplement 1).

Table 3. Controlled Time Series Analysis of Acute Care Encounters in 1-Year Olds After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)^a.

Outcome	Estimated effect of paid family leave (vs no leave)
Outcome	Observed monthly count	Predicted monthly count (95% PI)	Difference in counts (95% CI)^b^,^c	Relative percentage change (95% CI)^c^,^d
Any respiratory tract infection or associated symptoms
Jan 2018 to Mar 2018	23 461	23 650 (23 397-23 905)	−189 (−444 to 64)	−0.8 (−1.9 to 0.3)
Oct 2018 to Mar 2019	42 536	43 505 (43 064-43 957)	−969 (−1421 to −528)	−2.2 (−3.2 to −1.2)
Oct 2019 to Feb 2020	34 400	34 820 (34 332-35 315)	−420 (−915 to 68)	−1.2 (−2.6 to 0.2)
Total	100 397	101 975 (100 998-102 944)	−1578 (−2547 to −601)	−1.5 (−2.5 to −0.6)

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Abbreviation: PI, prediction interval.

^{^a}

^{^b}

Difference in counts = observed minus predicted

^{^c}

Confidence intervals calculated by bootstrapping 1000 samples.

^{^d}

Relative percentage change = 100 × (difference in counts) / predicted.

Discussion

Summary of Findings

We found acute care encounters for respiratory tract infections were 18% lower than expected among infants aged 8 weeks or younger after the introduction of New York state’s paid family leave policy, while RSV bronchiolitis acute care encounters were 27% lower than expected. Our finding that acute care encounters with respiratory tract infections among 1-year-olds were not meaningfully affected during this time supports the conclusion that the reductions observed in young infants were a direct effect of the policy rather than an incidental finding. Our findings suggest that US state-paid family leave policies can protect young infants from serious respiratory tract infections.

Comparison With the Literature

Previous research on the health impacts of paid family leave has focused primarily on maternal health (especially mental health) and maternal health behaviors, such as rates and duration of breastfeeding, timely administration of infant immunizations, and pediatric visit attendance, as well as infant mortality. Evidence on the effect of paid family leave on infant respiratory tract infection is scarce. An evaluation of California’s 2004 paid family leave found a 25% reduction in hospitalizations for upper respiratory tract infection and no reduction for lower respiratory tract infection after implementation. However, the study examined all hospitalizations to infants younger than 1 year, potentially masking a true effect for lower respiratory tract infection because the protective effect from reduced exposure to out-of-home childcare would primarily be restricted to the time during which paid family leave is usually taken (ie, the first 6 weeks after birth in California at the time of the study). Prior work from our team, motivating the present study, found a 30% lower RSV hospitalization rate in young infants after the introduction of New York’s paid family leave. Our prior study did not include control states, though, limiting our ability to conclude that the observed reduction was due to the policy rather than naturally milder RSV seasons in the years postpolicy. Furthermore, we did not have data on ED visits, leading to an incomplete assessment of the impact of paid leave on newborn respiratory health requiring acute medical care.

Clinical and Policy Implications

Although paid family leave policies are enacted for reasons unrelated to infant health (such as women’s labor force attachment), our findings highlight that there may be additional benefits of paid family leave that extend beyond those that motivated creation of the policy. Our evidence that paid family leave appears to protect young infants from serious respiratory illnesses may be useful in garnering support for paid leave legislation federally and in the 37 states that have not enacted paid family leave policies, as child health is a priority shared by politicians across the political spectrum.

Strengths and Limitations

Our evaluation of paid family leave was based on all recorded ED and hospital admission records, providing a comprehensive assessment of the policy’s impact at the population level. Our use of control states, as well as a placebo test, strengthen the likelihood that our findings reflect a true policy effect rather than other underlying trends. We used a time series analytic approach that explicitly modeled seasonality and severity of the viral season each year; in addition, we summarized the burden of acute care encounters across each respiratory virus seasons, providing an interpretable estimate of acute care encounters avoided.

A limitation of our study is that it was conducted before the introduction of new advances in RSV prevention in 2023: the introduction a maternal vaccine to prevent RSV in newborns and immunoprophylaxis of RSV in young infants with monoclonal antibody therapy. These changes make the temporal generalizability of our findings for RSV and lower respiratory tract infections unclear. However, our study found 22% lower rates of upper respiratory tract infection acute care encounters, suggesting broader benefits of the policy beyond RSV prevention. In addition, maternal vaccine uptake in pregnancy for other diseases (eg, influenza and tetanus, diphtheria, and pertussis) has historically been low and there is a potentially increased risk of preterm birth with maternal RSV vaccination, suggesting maternal vaccination strategies will provide incomplete protection. Given that efficacy for monoclonal antibodies in preventing medically attended RSV lower respiratory tract infection in young infants is estimated to be 79% and monoclonal antibody supply concerns have led to suboptimal coverage, we posit that paid family leave can still serve as an important layer in a Swiss cheese model for disease prevention.

Furthermore, we used ICD-CM codes to identify respiratory tract infections, which are subject to misclassification. However, our use of a broad case definition should decrease the impact of misclassification between types of respiratory tract illnesses and it is unlikely that misclassification occurred differentially in New York state and coincided with the introduction of the policy, which would both be necessary to introduce bias. Our use of 1-year-olds as a placebo test may have been compromised if they indirectly benefited from the introduction of paid family leave through removal of newborns from their group daycare. Also, our assumption that the paid family leave policy delayed the start of out-of-home childcare until after 8 weeks since birth was not based on published evidence from the New York paid family leave program. Lastly, our control states were less racially and ethnically diverse and had relatively more rural residents than New York state; however, the strong similarity of seasonal patterns of respiratory acute-care encounter rates among New York and controls states during the prepolicy period supports their use as controls to estimate the impact of New York’s policy.

Conclusions

Our findings provide evidence that a state-paid family leave policy may reduce acute care encounters for upper and lower respiratory tract infections, including RSV bronchiolitis, in young infants. This evidence of benefit for newborn health complements previous studies that have found benefits of paid family leave for maternal health.

Supplement 1.

eTable 1. ICD-10 diagnosis codes used to define each study outcome

eTable 2. Maternal characteristics of 1,376,362 live birth delivery hospitalizations in New York State as compared with control states (Maine, Massachusetts, New Hampshire, Vermont), Oct 2015-Feb 2020

eTable 3. Assessment of model fit pre-policy in controlled time series analysis of acute care encounters in infants ≤8 weeks of age after the introduction of paid family leave in New York State compared to control states (Maine, Massachusetts, New Hampshire, Vermont)

eTable 4: Controlled time series analysis of other study outcomes acute care encounters in infants ≤8 weeks of age after the introduction of paid family leave in New York State compared to control states (Maine, Massachusetts, New Hampshire, Vermont)

eFigure 1. Placebo control findings: Observed monthly rates of acute care encounters per 1000 one-year olds for any respiratory tract infection (RTI) and associated symptoms after the introduction of paid family leave in New York State compared to control states (Maine, Massachusetts, New Hampshire, Vermont [shown on secondary axis]), Oct 2015-Feb 2020

eFigure 2. Placebo control findings: observed and predicted monthly rates of acute care encounters per 1000 one-year olds for any respiratory tract infection (RTI) and associated symptoms after the introduction of paid family leave in New York State, Oct 2015-Feb 2020

eAppendix. Statistical model and Stata code

jamapediatr-e243184-s001.pdf^{(364.2KB, pdf)}

Supplement 2.

Data sharing statement

jamapediatr-e243184-s002.pdf^{(14.4KB, pdf)}

References

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14.Huang R, Yang M. Paid maternity leave and breastfeeding practice before and after California’s implementation of the nation’s first paid family leave program. Econ Hum Biol. 2015;16:45-59. doi: 10.1016/j.ehb.2013.12.009 [DOI] [PubMed] [Google Scholar]
15.Hamad R, Modrek S, White JS. Paid family leave effects on breastfeeding: a quasi-experimental study of US policies. Am J Public Health. 2019;109(1):164-166. doi: 10.2105/AJPH.2018.304693 [DOI] [PMC free article] [PubMed] [Google Scholar]
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22.Suh M, Movva N, Jiang X, et al. Respiratory syncytial virus is the leading cause of United States infant hospitalizations, 2009-2019: a study of the national (nationwide) inpatient sample. J Infect Dis. 2022;226(suppl 2):S154-S163. doi: 10.1093/infdis/jiac120 [DOI] [PMC free article] [PubMed] [Google Scholar]
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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplement 1.

eTable 1. ICD-10 diagnosis codes used to define each study outcome

eAppendix. Statistical model and Stata code

jamapediatr-e243184-s001.pdf^{(364.2KB, pdf)}

Supplement 2.

Data sharing statement

jamapediatr-e243184-s002.pdf^{(14.4KB, pdf)}

[poi240058r1] 1.Weiss AJ, Liang L, Martin K. Statistical brief 299: overview of hospital stays among children and adolescents, 2019. Accessed July 22, 2024. https://www.hcup-us.ahrq.gov:443/reports/statbriefs/sb299-Hospital-Stays-Children-2019.pdf [PubMed]

[poi240058r2] 2.McDermott KW, Stocks C, Freeman WJ. Overview of Pediatric Emergency Department Visits, 2015: Statistical Brief #242. Healthcare Cost and Utilization Project (HCUP) Statistical Briefs. Agency for Healthcare Research and Quality; 2018. [PubMed] [Google Scholar]

[poi240058r3] 3.Hall CB, Weinberg GA, Blumkin AK, et al. Respiratory syncytial virus-associated hospitalizations among children less than 24 months of age. Pediatrics. 2013;132(2):e341-e348. doi: 10.1542/peds.2013-0303 [DOI] [PubMed] [Google Scholar]

[poi240058r4] 4.Nesti MM, Goldbaum M. Infectious diseases and daycare and preschool education. J Pediatr (Rio J). 2007;83(4):299-312. doi: 10.2223/JPED.1649 [DOI] [PubMed] [Google Scholar]

[poi240058r5] 5.Kamper-Jørgensen M, Wohlfahrt J, Simonsen J, Grønbaek M, Benn CS. Population-based study of the impact of childcare attendance on hospitalizations for acute respiratory infections. Pediatrics. 2006;118(4):1439-1446. doi: 10.1542/peds.2006-0373 [DOI] [PubMed] [Google Scholar]

[poi240058r6] 6.Jou J, Kozhimannil KB, Abraham JM, Blewett LA, McGovern PM. Paid maternity leave in the United States: associations with maternal and infant health. Matern Child Health J. 2018;22(2):216-225. doi: 10.1007/s10995-017-2393-x [DOI] [PubMed] [Google Scholar]

[poi240058r7] 7.Ranji ULM, Frederiksen B, Diep K, Salganicoff A. Workplace benefits and family health care responsibilities: key findings from the 2022 KFF Women’s Health Survey. Accessed July 22, 2024. https://www.kff.org/womens-health-policy/issue-brief/workplace-benefits-and-family-health-care-responsibilities-key-findings-from-the-2022-kff-womens-health-survey/

[poi240058r8] 8.Lerner S. The real war on families: why the US needs paid leave now. Accessed July 22, 2024. https://inthesetimes.com/article/18151/the-real-war-on-families

[poi240058r9] 9.Klerman JADK, Pozniak A; US Department of Labor . Family and medical leave in 2012: technical report. Accessed July 22, 2024. https://www.dol.gov/sites/dolgov/files/OASP/legacy/files/FMLA-2012-Technical-Report.pdf

[poi240058r10] 10.Trajkovski S. California paid family leave and parental time use. Accessed July 22, 2024. https://surface.syr.edu/cpr/249/

[poi240058r11] 11.Center for Women and Work, Rutgers School of Management and Labor Relations . Implementation of paid family leave in New Jersey: a promising work in progress. Accessed July 22, 2024. https://smlr.rutgers.edu/sites/default/files/Documents/Implementation_PaidFamilyLeave_Oct2021.pdf

[poi240058r12] 12.Mirkovic KR, Perrine CG, Scanlon KS. Paid maternity leave and breastfeeding outcomes. Birth. 2016;43(3):233-239. doi: 10.1111/birt.12230 [DOI] [PubMed] [Google Scholar]

[poi240058r13] 13.Van Niel MS, Bhatia R, Riano NS, et al. The impact of paid maternity leave on the mental and physical health of mothers and children: a review of the literature and policy implications. Harv Rev Psychiatry. 2020;28(2):113-126. doi: 10.1097/HRP.0000000000000246 [DOI] [PubMed] [Google Scholar]

[poi240058r14] 14.Huang R, Yang M. Paid maternity leave and breastfeeding practice before and after California’s implementation of the nation’s first paid family leave program. Econ Hum Biol. 2015;16:45-59. doi: 10.1016/j.ehb.2013.12.009 [DOI] [PubMed] [Google Scholar]

[poi240058r15] 15.Hamad R, Modrek S, White JS. Paid family leave effects on breastfeeding: a quasi-experimental study of US policies. Am J Public Health. 2019;109(1):164-166. doi: 10.2105/AJPH.2018.304693 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r16] 16.Berger LM, Hill J, Waldfogel J. Maternity leave, early maternal employment and child health and development in the US. Econ J (Lond). 2005;115(501):F29-F47. doi: 10.1111/j.0013-0133.2005.00971.x [DOI] [Google Scholar]

[poi240058r17] 17.New York State . New York state paid family leave. year in review. Accessed July 24, 2024. paidfamilyleave.ny.gov

[poi240058r18] 18.National Partnership for Women and Families . State paid leave laws. Accessed July 22, 2024. https://nationalpartnership.org/economic-justice/state-paid-leave-laws/

[poi240058r19] 19.New York State . Paid family leave: year in review 2018. Accessed July 22, 2024. https://www.governor.ny.gov/sites/default/files/atoms/files/PFL_EOYReport_2018_FINAL.pdf

[poi240058r20] 20.Bana S, Bedard K, Rossin-Slater M. Trends and disparities in leave use under California’s paid family leave program: new evidence from administrative data. AEA Pap Proc. 2018;108:388-391. doi: 10.1257/pandp.20181113 [DOI] [Google Scholar]

[poi240058r21] 21.Nguyen T, Dennison BA, Radigan A, FitzPatrick E, Zhang W, Ncube B. New York state’s paid family leave program is associated with more equitable and increased use of paid leave following childbirth. Matern Child Health J. 2023;27(3):516-526. doi: 10.1007/s10995-022-03510-6 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r22] 22.Suh M, Movva N, Jiang X, et al. Respiratory syncytial virus is the leading cause of United States infant hospitalizations, 2009-2019: a study of the national (nationwide) inpatient sample. J Infect Dis. 2022;226(suppl 2):S154-S163. doi: 10.1093/infdis/jiac120 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r23] 23.New York State Senate . Article 9: Disability Benefits Law and the Paid Family Leave Benefits Law. Accessed July 22, 2024. https://www.nysenate.gov/legislation/laws/WKC/A9

[poi240058r24] 24.Agency for Healthcare Research and Quality . Clinical classifications software refined. Accessed July 22, 2024. https://hcup-us.ahrq.gov/toolssoftware/ccsr/ccs_refined.jsp

[poi240058r25] 25.Alliance for Innovation on Maternal Health . Severe maternal morbidity code list for identifying denominator deliveries. Accessed July 22, 2024. https://saferbirth.org/aim-resources/implementation-resources/

[poi240058r26] 26.Matias G, Taylor R, Haguinet F, Schuck-Paim C, Lustig R, Shinde V. Estimates of hospitalization attributable to influenza and RSV in the US during 1997-2009, by age and risk status. BMC Public Health. 2017;17(1):271. doi: 10.1186/s12889-017-4177-z [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r27] 27.Thompson WW, Shay DK, Weintraub E, et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA. 2003;289(2):179-186. doi: 10.1001/jama.289.2.179 [DOI] [PubMed] [Google Scholar]

[poi240058r28] 28.Bardsley M, Morbey RA, Hughes HE, et al. Epidemiology of respiratory syncytial virus in children younger than 5 years in England during the COVID-19 pandemic, measured by laboratory, clinical, and syndromic surveillance: a retrospective observational study. Lancet Infect Dis. 2023;23(1):56-66. doi: 10.1016/S1473-3099(22)00525-4 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r29] 29.Hamid S, Winn A, Parikh R, et al. Seasonality of respiratory syncytial virus—United States, 2017-2023. MMWR Morb Mortal Wkly Rep. 2023;72(14):355-361. doi: 10.15585/mmwr.mm7214a1 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r30] 30.Shi X, Miao W, Tchetgen ET. A selective review of negative control methods in epidemiology. Curr Epidemiol Rep. 2020;7(4):190-202. doi: 10.1007/s40471-020-00243-4 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r31] 31.Thoma ME, Copen CE, Kirmeyer SE. Short interpregnancy intervals in 2014: differences by maternal demographic characteristics. NCHS Data Brief. 2016;(240):1-8. [PubMed] [Google Scholar]

[poi240058r32] 32.Lee BC, Modrek S, White JS, Batra A, Collin DF, Hamad R. The effect of California’s paid family leave policy on parent health: a quasi-experimental study. Soc Sci Med. 2020;251:112915. doi: 10.1016/j.socscimed.2020.112915 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r33] 33.Montoya-Williams D, Passarella M, Lorch SA. The impact of paid family leave in the United States on birth outcomes and mortality in the first year of life. Health Serv Res. 2020;55 suppl 2(suppl 2):807-814. doi: 10.1111/1475-6773.13288 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r34] 34.Pihl AM, Basso G. Did California paid family leave impact infant health?. J Policy Anal Manage. 2019;38(1):155-80 [PubMed] [Google Scholar]

[poi240058r35] 35.Hutcheon JA, Janevic T, Ahrens KA. Respiratory syncytial virus bronchiolitis hospitalizations in young infants after the introduction of paid family leave in New York state, 2015–2019. Am J Public Health. 2022;112(2):316-324. doi: 10.2105/AJPH.2021.306559 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r36] 36.Flint SS. How bipartisanship and incrementalism stitched the child health insurance safety net (1982-1997). Health Soc Work. 2014;39(2):109-116. doi: 10.1093/hsw/hlu019 [DOI] [PubMed] [Google Scholar]

[poi240058r37] 37.Yonts AB, Gaviria-Agudelo C, Kimberlin DW, O’Leary ST, Paulsen GC. ACIP update on meningococcal, RSV, covid-19, and other pediatric vaccines. Pediatrics. 2023;2023. doi: 10.1542/peds.2023-064990 [DOI] [PubMed] [Google Scholar]

[poi240058r38] 38.Simões EAF, Madhi SA, Muller WJ, et al. Efficacy of nirsevimab against respiratory syncytial virus lower respiratory tract infections in preterm and term infants, and pharmacokinetic extrapolation to infants with congenital heart disease and chronic lung disease: a pooled analysis of randomised controlled trials. Lancet Child Adolesc Health. 2023;7(3):180-189. doi: 10.1016/S2352-4642(22)00321-2 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r39] 39.Rand CM, Olson-Chen C. Maternal vaccination and vaccine hesitancy. Pediatr Clin North Am. 2023;70(2):259-269. doi: 10.1016/j.pcl.2022.11.004 [DOI] [PMC free article] [PubMed] [Google Scholar]

[poi240058r40] 40.Dieussaert I, Hyung Kim J, Luik S, et al. RSV prefusion F protein-based maternal vaccine—preterm birth and other outcomes. N Engl J Med. 2024;390(11):1009-1021. doi: 10.1056/NEJMoa2305478 [DOI] [PubMed] [Google Scholar]

[poi240058r41] 41.US Food and Drug Administration . FDA approves first vaccine for pregnant individuals to prevent RSV in infants. Accessed July 22, 2024. https://www.fda.gov/news-events/press-announcements/fda-approves-first-vaccine-pregnant-individuals-prevent-rsv-infants

[poi240058r42] 42.US Centers for Disease Control and Prevention . Limited availability of Nirsevimab in the United States—interim CDC recommendations to protect infants from respiratory syncytial virus (RSV) during the 2023–2024 respiratory virus season. Accessed July 22, 2024. https://emergency.cdc.gov/han/2023/han00499.asp

[poi240058r43] 43.Reason J. The contribution of latent human failures to the breakdown of complex systems. Philos Trans R Soc Lond B Biol Sci. 1990;327(1241):475-484. doi: 10.1098/rstb.1990.0090 [DOI] [PubMed] [Google Scholar]

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Paid Family Leave and Prevention of Acute Respiratory Infections in Young Infants

Katherine A Ahrens, PhD

Teresa Janevic, PhD

Erin C Strumpf, PhD

Arijit Nandi, PhD

Justin R Ortiz, MD

Jennifer A Hutcheon, PhD

Key Points

Question

Findings

Meaning

Abstract

Importance

Objective

Design, Setting, and Participants

Intervention

Main Outcomes and Measures

Results

Conclusions

Introduction

Methods

Hypothesis

Data

Paid Family Leave Policy in New York State

Primary Outcome: Acute Care Encounters for Respiratory Tract Infection

Secondary Outcome: Acute Care Encounters for RSV

Additional Study Outcomes

Denominator

Statistical Analysis

Placebo Test

Results

Acute Care Encounters for Respiratory Tract Infection

Table 1. Characteristics of Acute Care Encounters (Hospitalization and Emergency Department Visits) in Infants 8 Weeks or Younger for Respiratory Tract Infection and Related Symptoms in New York State as Compared With Control States, October 2015 through February 2020a.

Figure 1. Observed Monthly Rates of Acute Care Encounters per 1000 Infants 8 Weeks or Younger.

Figure 2. Observed and Predicted Monthly Rates of Acute Care Encounters per 1000 Infants 8 Weeks or Younger.

Table 2. Controlled Time Series Analysis of Acute Care Encounters in Infants 8 Weeks or Younger After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)a.

Respiratory Syncytial Virus

Other Study Outcomes

Placebo Test

Table 3. Controlled Time Series Analysis of Acute Care Encounters in 1-Year Olds After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)a.

Discussion

Summary of Findings

Comparison With the Literature

Clinical and Policy Implications

Strengths and Limitations

Conclusions

References

Associated Data

Supplementary Materials

ACTIONS

PERMALINK

RESOURCES

Similar articles

Cited by other articles

Links to NCBI Databases

Table 1. Characteristics of Acute Care Encounters (Hospitalization and Emergency Department Visits) in Infants 8 Weeks or Younger for Respiratory Tract Infection and Related Symptoms in New York State as Compared With Control States, October 2015 through February 2020^a.

Table 2. Controlled Time Series Analysis of Acute Care Encounters in Infants 8 Weeks or Younger After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)^a.

Table 3. Controlled Time Series Analysis of Acute Care Encounters in 1-Year Olds After the Introduction of Paid Family Leave in New York State Compared With Control States (Maine, Massachusetts, New Hampshire, Vermont)^a.