Table 2. Characteristics and Adjusted Cofounders of Studies Included in the Meta-Analysis.

First Author, (Ref), Year, Country	Study Design	Study size (Mother-Child Pairs)	Type of HAP + Monitoring Type	Mother Time of Exposure Recording	Child Respiratory Diagnosis Method	Child Age/Frequency of Diseases Recording	Child Respiratory Illness Assessed	Matched or Adjusted Factors	Risk Estimates (95% CI)
Lee et al. [12], 2019, Ghana, West Africa	Prospective Cohort Study	404	CO + CO monitoring (Lascar EL-CO-USB Data Logger)	(24 weeks) Third Trimester Pregnancy	Doctor diagnosed at Kintampo Municipal Hospital	Weekly home visits first year	Physician-assessed pneumonia (PNA) and Severe PNA (SPNA)	Birth weight and Gestational age	Physician- assessed (PNA) 1.02 (1.00-1/04) and PNA 1.04 (1.00-1.04)
Kinney et al. [11], 2021, Ghana, West Africa	Cohort Study	1141	CO +Lascar EL-CO-USB	(24 Weeks) Third Trimester Pregnancy	Fieldworkers performed	Weekly home visits first year	Physician-assessed pneumonia (PNA) and Severe PNA (SPNA)	All covariates adjusted as stated: not specified what the covariates were	Pneumonia 1.10 (1.04-1.16) Severe Pneumonia 1.06 (0.99-1.13)
Seeni et al. [10], 2018, US	Cohort Study	223,375	CO NOx, O3, Pm10, PM 2.5, SO2 + Community Multiscale Air Quality	All trimesters	Newborn ERMs + Summary Discharge	Neonate, one time	Transient Tachypnea, Asphyxia, Respiratory distress	Gestational age, maternal age, race, smoking or alcohol use during pregnancy	TTN from CO: 1.1 (1-1.2) RDS from NOx: 1.03 (-0.95-1.1) RDS from O3: 0.98 (.92-1.04) TTN PM10: 1.02 (0.96-1.1) Asphyxia from PM 2.5: 1.2 (1.1-1.3) No significant association from SO2: 0.72 (0.65-0.79)
Liu et al. [15], 2016, Shanghai, China	Cross-Sectional Study	3358	NO2, SO2, PM10, + Aerodynamic Diameter	All gestation periods	Doctor-Diagnosed	First 2-3 years, once	Asthma, Allergic Rhinitis	All covariates adjusted as stated: not specified what the covariates were	Asthma from NO2: 1.77 (1.29-2.43) Allergic Rhinitis from NO2: 1.67 (1.07-2.61) No association from SO2 and PM10
Jedrychowski et al. [19], 2010, Krakow, Poland	Cohort Study	339	PAH, PM 2.5 + Personal Exposure Monitor	First or Second Trimester	Reported by Mothers	First 2 years of Child, every 2 months	Wheezing Days	Environmental tobacco smoke (ETS), gender of child, maternal characteristics (age, education and atopy), parity, and mold/dampness in the home	PAH 1.69 (1.52-1.88) PM 2.5 1.38 (1.25-1.51)
Lin et al. [18], 2021, Taichung, Taiwan	Cohort Study	140,911	PM 2.5 + Satellite-based hybrid model	30 gestational weeks - birth	Hospital Records	2.97 +/ 1.78 years, once	Allergic Rhinitis	All covariates adjusted as stated: not specified what the covariates were	1.025 (1.00 -1.05)
Wright et al. [20], 2021, US	Longitudinal cohort study	376	UFP + spatiotemporally	37 weeks	Maternal Reports	4 month intervals from birth to 30 months	Asthma	Maternal age, education, race, and obesity; child sex; nitrogen dioxide (NO2) and temperature averaged over gestation	4.28 (1.41-15.7)
Guo et al. [14], 2020 Wuhan, China	Observational Cohort Study	332	SO2, NO2, PM10, PM2.5 + Air quality Monitoring stations	Second Trimester	Parents Reported	Not Specified	Allergic Diseases: Asthma, Allergic Rhinitis, Allergic Conjunctivitis or/and eczema	All covariates adjusted as stated: not specified what the covariates were	Mentioned diseases from NO2 1.292 (1.005,1.662) Mentioned diseases from PM10 1.210 (1.042-1.405) Mentioned diseases from PM2.5 1.270 (1.004,1.606) No significant association from SO2
Madsen et al. [13], 2017, Oslo and Bergen, Norway	Cohort Study	17,533	NO2 + Lan Ude Regression	All trimesters	Maternal Surveys	0-6 Months, once	Lower Respiratory Tract Infections (syncytial virus, bronchiolitis, bronchitis and pneumonia) and Wheezing	Age at delivery, maternal marital status, maternal education, sex of child, maternal pre-pregnancy BMI, parity, year of birth, smoking during pregnancy, maternal atopy and area	0.99 (.84-1.17)
Rivera et al. [17], 2022, Mexico City, Mexico	Observational Cohort Study	535	PM 2.5 _ Satellite-based-spatio-temporal model	14 weeks - birth	Maternal Reports	6-8 years, once	Wheeze	Child sex, birth weight for gestational age z-score, maternal asthma, educational attainment at enrollment (<high school, some high school or high school graduate, >high school)	3.76 (1.41, 10)
Zhang et al. [16], 2021, Central China	Cross-sectional Questionnaire	5788	PM 1 Spatiotemporal Models	All trimester	Maternal Report	3-5 years, once	Asthma + Wheezing	Maternal smoking status, age at delivery, breast-feeding duration, birth weight, gestational week, family history, maternal education	1.618 (1.159-2.258) 1.543 (0.822-2.896)