Kathiravan Anoushka, Schauer Zoe R, Wojcicki Janet M
Pediatric Gastroenterology, Hepatology and Nutrition, University of California, San Francisco, CA, USA.
Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
J Epidemiol Glob Health. 2025 May 19;15(1):72. doi: 10.1007/s44197-025-00415-9.
The COVID-19 lockdown impacted interactions with the health care system and societal stress levels. Previous US-based studies suggest that pandemic lockdowns may have lowered preterm birth rates although there are mixed findings from different settings. We evaluated the impact of COVID-19 on preterm birth and low birthweight rates at two San Francisco hospitals.
We compared rates of preterm birth (< 37 weeks) and low birthweight (< 2500 g) in San Francisco at a safety net hospital and an academic medical center during two time periods early in the COVID-19 pandemic compared with the same months from the prior year: from March to May 2019 and 2020 and August to December 2019 and 2020. We calculated crude rates for preterm birth and low birth weight as well as compared maternal and infant birth demographics and health characteristics during these same time periods using descriptive statistics. Secondly using a cross-sectional study design, we used logistic and linear regression models to evaluate risk for preterm birth, gestational age at birth, and low birthweight adjusting for confounders comparing the lockdown period with the pre-COVID year. All analyses were conducted using Stata 15.0.
From August to December 2019 to 2020, the preterm birth rate decreased from 13.20 to 7.96% in the combined hospital data (p < 0.01), and the low birthweight rate decreased from 11.33 to 9.70% during the same time period (p = 0.13). We did not find a comparable reduction from March to May 2019 to 2020. Maternal age at delivery was significantly younger during the lockdown period, August to December, than in the prior year (36.29 ± 5.69 versus 37.15 ± 5.68 years p < 0.01) and parity was greater (0.83 ± 1.15 versus 0.74 ± 1.04, p = 0.03) but there were no other significant differences in race or ethnicity, infant sex or type of delivery (vaginal versus Cesarean section) from 2019 to 2020. In a logistic and linear regression model adjusting for maternal age and infant sex and other confounders, the lockdown period from August to December was protective against preterm birth (OR 0.65, 95%CI 0.51-0.82) and associated with overall longer gestational duration (Coeff 0.23, 95%CI 0.07-0.39). The August to December lockdown period was also associated with greater birthweight (Coeff 43.76, 95%CI 2.19-85.34).
In San Francisco, COVID-19 lockdowns lowered the preterm birth and increased gestational duration in infants comparing 2019 with 2020 for August to December. The reduced in preterm birth rates may be related to the overall strict lockdown measures that San Francisco implemented compared with other US cities. WHAT THIS STUDY ADDS TO THE CLINICAL WORK?: This study suggests that COVID-19 lockdowns lowered the preterm birth rate in August -December 2020 compared with the same months in 2019 in two hospitals in San Francisco. San Francisco had strict lockdowns compared with other areas of the country and fewer deaths. The stay-at-home measures could possibly have reduced stress for pregnant women or had other positive benefits that reduced the preterm birth rate.
新冠疫情封锁措施影响了与医疗系统的互动以及社会压力水平。此前美国的研究表明，疫情封锁可能降低了早产率，不过不同地区的研究结果不一。我们评估了新冠疫情对旧金山两家医院早产率和低出生体重率的影响。
我们比较了新冠疫情早期两个时间段（2019年3月至5月以及2020年同期，2019年8月至12月以及2020年同期）旧金山一家安全网医院和一家学术医疗中心的早产（<37周）率和低出生体重（<2500克）率。我们计算了早产和低出生体重的粗发生率，并使用描述性统计方法比较了同一时期的孕产妇和婴儿出生人口统计学特征及健康特征。其次，采用横断面研究设计，我们使用逻辑回归和线性回归模型评估早产风险、出生孕周以及低出生体重，并对混杂因素进行调整，将封锁期与新冠疫情前一年进行比较。所有分析均使用Stata 15.0进行。
从2019年8月至12月到2020年同期，综合医院数据中的早产率从13.20%降至7.96%（p<0.01），同期低出生体重率从11.33%降至9.70%（p=0.13）。我们未发现2019年3月至5月到2020年同期有类似的下降情况。在8月至12月的封锁期，分娩时的产妇年龄显著低于上一年（36.29±5.69岁对37.15±5.68岁，p<0.01），产次更高（0.83±1.15对0.74±1.04，p=0.03），但2019年至2020年在种族或民族、婴儿性别或分娩方式（阴道分娩与剖宫产）方面没有其他显著差异。在调整了产妇年龄、婴儿性别和其他混杂因素的逻辑回归和线性回归模型中，8月至12月的封锁期可预防早产（OR 0.65，95%CI 0.51-0.82），并与总体较长的孕周相关（系数0.23，95%CI 0.07-0.39）。8月至12月的封锁期还与更高的出生体重相关（系数43.76，95%CI 2.19-85.34）。
在旧金山，与2019年相比，2020年8月至12月的新冠疫情封锁降低了早产率并延长了婴儿的孕周。早产率的降低可能与旧金山实施的总体严格封锁措施有关，与美国其他城市相比情况不同。本研究对临床工作的补充：本研究表明，与2019年同期相比，2020年8月至12月旧金山两家医院的新冠疫情封锁降低了早产率。与美国其他地区相比，旧金山实施了严格的封锁措施，死亡人数较少。居家措施可能减轻了孕妇的压力或带来了其他积极益处，从而降低了早产率。
