Table 1. Baseline Characteristics of Mothers With a Singleton Live Birth by Exposure to BNT162b2 Vaccination During Pregnancy.
| Pre-IPTWa | Post-IPTW | |||||
|---|---|---|---|---|---|---|
| Unvaccinated (n = 7591) | Vaccinated (n = 16 697) | Absolute SMDb | Unvaccinated (n = 7452) | Vaccinated (n = 16 738) | Absolute SMDb | |
| Maternal age, mean (SD), y | 30.49 (5.67) | 31.61 (5.22) | 0.21 | 31.1 (5.6) | 31.2 (5.3) | 0.02 |
| Infant sex, No. (%) | 0.01 | 0.01 | ||||
| Female | 3729 (49.1) | 8111 (48.6) | 3684 (49.4) | 8160 (48.8) | ||
| Male | 3862 (50.9) | 8586 (51.4) | 3768 (50.6) | 8578 (51.2) | ||
| Parity, No. (%) | 5107 (67.3) | 11 142 (66.7) | 0.01 | 5013 (67.3) | 11 212 (67.0) | 0.01 |
| Trimester at first vaccine dose (wk), No. (%) | ||||||
| First (<14) | 2134 (12.8) | 1851 (11.1) | ||||
| Second (14-26) | 9364 (56.1) | 8996 (53.7) | ||||
| Third (≥27) | 5199 (31.1) | 5891 (35.2) | ||||
| Socioeconomic status, mean (SD)c | 5.17 (1.98) | 6.13 (2.02) | 0.48 | 5.7 (2.04) | 5.8 (2.07) | 0.04 |
| Population subgroup, No. (%)d | 0.35 | 0.03 | ||||
| Arab | 830 (10.9) | 714 (4.3) | 495 (6.6) | 1072 (6.4) | ||
| Jewish, secular | 4847 (63.9) | 13 145 (78.7) | 5407 (72.6) | 12 328 (73.7) | ||
| Ultra-Orthodox | 1914 (25.2) | 2838 (17.0) | 1550 (20.8) | 3338 (19.9) | ||
| Preexisting maternal comorbidities, No. (%) | ||||||
| Obesity (BMI ≥30) | 862 (11.4) | 1768 (10.6) | 0.03 | 828 (11.1) | 1780 (10.6) | 0.02 |
| Infertility | 84 (1.1) | 304 (1.8) | 0.06 | 129 (1.7) | 260 (1.6) | 0.02 |
| Cancer | 55 (0.7) | 168 (1.0) | 0.03 | 66 (0.9) | 158 (0.9) | 0.01 |
| Hypertension | 76 (1.0) | 159 (1.0) | 0.01 | 74 (1.0) | 158 (0.9) | 0.01 |
| Chronic kidney disease | 67 (0.9) | 118 (0.7) | 0.02 | 75 (1.0) | 114 (0.7) | 0.04 |
| Diabetes | 59 (0.8) | 145 (0.9) | 0.01 | 72 (1.0) | 133 (0.8) | 0.02 |
| Cardiovascular disease | 2 (<0.1) | 8 (<0.1) | 0.01 | 2 (<0.1) | 8 (<0.1) | 0.01 |
| Chronic obstructive pulmonary disease | 2 (<0.1) | 3 (<0.1) | 0.01 | 1 (<0.1) | 3 (<0.1) | 0.00 |
| Smoking | 0.09 | 0.083 | ||||
| Ever | 441 (5.8) | 798 (4.8) | 470 (6.3) | 793 (4.7) | ||
| Never | 7099 (93.5) | 15 865 (95.0) | 6937 (93.1) | 15 909 (95.1) | ||
| Missing | 51 (0.7) | 34 (0.2) | 45 (0.6) | 36 (0.2) | ||
| Maternal SARS-CoV-2 infection | ||||||
| Before birth | 2241 (29.5) | 1078 (6.5) | 0.63 | 2255 (30.3) | 1108 (6.6) | 0.64 |
| Preconception | 383 (5.0) | 354 (2.1) | 0.16 | 448 (6.0) | 358 (2.1) | 0.20 |
| Seasonal influenza vaccine | 1535 (20.2) | 7131 (42.7) | 0.50 | 2469 (33.1) | 5924 (35.4) | 0.05 |
| Pertussis vaccine | 4698 (61.9) | 13 949 (83.5) | 0.50 | 4902 (65.8) | 13 663 (81.6) | 0.37 |
| Gestational diabetes | 156 (2.1) | 314 (1.9) | 0.01 | 159 (2.1) | 315 (1.9) | 0.02 |
| High-risk pregnancy | 842 (11.1) | 1786 (10.7) | 0.01 | 842 (11.3) | 1760 (10.5) | 0.03 |
| Calendar conception median (IQR), mo | 8 (6-10) | 9 (7-11) | 0.29 | 9 (7-11) | 9 (7-11) | 0.06 |
Abbreviations: BMI, body mass index; IPTW, inverse probability of treatment weights; SMD, standardized mean difference.
Propensity adjustment via IPTW was used to balance groups in terms of maternal age, conception timing, parity, seasonal influenza vaccination, population subgroup, and socioeconomic status. Post-IPTW numbers slightly differ from crude pre-IPTW because of propensity weighting.
SMD is the difference between the groups’ means divided by the pooled SD; <0.1 is considered a minor difference.
Residential area socioeconomic status was a score ranked from 1 (lowest) to 10 derived by the Israel Central Bureau of Statistics census data.
Population subgroup was assessed by enumeration areas (the Israeli census smallest unit of analysis) with a high proportion of Jewish Orthodox and Israeli Arab residents according to voting results, spatial presence of religious schools, religious centers such as synagogues or mosques, and other publicly available databases.