The early COVID-19 pandemic period and associated gestational weight gain

Introduction

Gestational weight gain is an important controllable factor in maternal and fetal outcomes. Low or excessive gestational weight gain are risk factors for increased adverse pregnancy outcomes [1]. The most recent data from the US reporting on gestational weight gain showed the prevalence of low weight gain was 21 % and for excessive weight gain was 48 %. The prevalence of excessive gestational weight gain was exacerbated in overweight and obese individuals [2].

In the US, guidelines for normal gestational weight gain are provided by the Institute of Medicine (IOM) which are based on type of gestation (singleton vs. multiple) and pre-pregnancy body mass index (BMI) with ranges for underweight, normal weight, overweight and obese as defined by the World Health organization (WHO) [3]. Excessive gestational weight gain is associated with increased risk of numerous pregnancy complications including gestational diabetes, hypertensive disorders of pregnancy, venous thromboembolism, preterm birth, labor dystocia, cesarean section, hemorrhage, and infection [4]. Infants born to individuals with excessive gestational weight gain are at increased risk of morbidity and mortality due to effects of prematurity, large for gestational age, and low birthweight, even in the absence of co-occurring pregnancy and maternal complications. For pregnant individuals with low gestational weight gain, the risk of preterm birth and low birth weight is significantly higher even in the absence of other co-morbidities [4]. The start of the Coronavirus Disease 2019 (COVID-19) pandemic disrupted many aspects of routine life. Individuals were limited in their usual level of physical activity, due to stay at home recommendations. Additionally, gym closures and social distancing further limited individuals’ usual physical activity levels. Decreased physical activity is a known risk factor for excessive gestational weight gain [5]. In addition to the limitations on physical activity, increased isolation, which was also seen at the start of the COVID-19 pandemic was found to impact the incidence of obesity and gestational weight gain in pregnant populations in China, Italy, and Austria [6], [7], [8], [9].

The effects of COVID-19 pandemic and resultant shutdowns and social distancing polices on gestational weight gain in the US are mixed based on prior research conducted in the US. Two national-level studies, along with research from Louisiana and Washington state, showed a slight increase in gestational weight gain during the pandemic [10], [11], [12], [13]. In contrast, a study from New York reported a decrease in gestational weight gain during the same period [14], while studies from Tennessee and South Carolina, as well as a randomized controlled trial involving military personnel and their dependents, found no significant effect of the pandemic on gestational weight gain [15], [16], [17]. One of the limitations of the national-level studies is the data was not stratified by state to understand the impact the COVID-19 pandemic had on individual states. We sought to understand how the COVID-19 pandemic may have impacted gestational weight gain in pregnant individuals in our local community.

Materials and methods

We conducted a retrospective cohort study of patients with singleton gestations who were delivered at an urban academic medical center in Connecticut before and during the early phase of the COVID-19 pandemic. The study excluded individuals with missing data on pre-pregnancy BMI as well as those with a diagnosis of pre-gestational diabetes. These data were obtained from the hospital electronic medical record (EMR).

The primary exposure was the early phase of the COVID-19 pandemic, and this epoch was defined as March 10, 2020, to December 31, 2020. The pandemic epoch was compared to matched months in 2018 and 2019, which was defined as the pre-pandemic epoch [18]. Individuals were included if their LMP was≤20 weeks’ gestation at the start of these periods with estimated due dates at the end of the defined period (March to December of each year included). The pandemic period was further stratified to groups with individuals who were <14 weeks’ gestation and between 14 and ≤20 weeks gestational age (GA) at the start of pandemic exposure to permit assessment of the effects of timing of antenatal exposure on gestational weight gain.

Demographic characteristics included age, self-reported race/ethnicity (non-Hispanic White, non-Hispanic Black, Hispanic, and non-Hispanic Asian/other), insurance type (commercial, other (Medicaid/Medicare, other, unknown, self-pay, missing)), and marital status (married, not married (single, divorced, widowed, live as married, other).

Pre-pregnancy BMI was classified as underweight (<18.5 kg/m²), normal weight (18.5–24.9 kg/m²), overweight (25–29.9 kg/m²) and obese (≥30 kgm²) per WHO criteria [19]. At our institution, pre-pregnancy BMI was measured at the first prenatal if the first trimester or self-reported if the first prenatal visit was after the first trimester. Height is typically self-reported or pulled from existing data except if not known by the individual or are new in the health system.

ICD codes were used to identify patients with gestational diabetes, chronic hypertension, and hypertensive disorders of pregnancy. At our institution, the diagnosis of gestational diabetes is determined from glucose tolerance test between 24 and 28 weeks’ gestation per Carpenter-Coustan criteria [20]. Our hypertension variable was a mutually exclusive four-level categorical variable defined as no evidence of any hypertensive disease, chronic hypertension, hypertensive disorders of pregnancy, and both chronic hypertension and superimposed pregnancy induced hypertension. Hypertensive disorders of pregnancy encompass gestational hypertension, pre-eclampsia, eclampsia, and HELLP syndrome as described in the American College of Obstetrics and Gynecology practice bulletin [21]. Additional demographic and clinical information abstracted from the EMR included smoking status, metformin use in pregnancy, selective serotonin reuptake inhibitor (SSRI) use, any encounter for telehealth visits during prenatal care (only available after the start of the COVID-19 pandemic and was optional or offered at the discretion of the provider) and nutrition consult during pregnancy. Nutrition consults in our practice consist of a 60 min in-person or telehealth visit with a registered dietician where individuals receive counseling on recommended weight gain in pregnancy as well as food and meal suggestions to reach recommended macronutrient targets and are offered to individuals with obesity or other medical conditions during pregnancy.

The primary outcome was maternal weight gain at delivery which was measured prior to delivery in the hospital. IOM recommends 28–40 pounds weight gain for underweight individuals, 25–35 pounds for normal weight individuals, 15–25 pounds for overweight individuals and 11–20 pounds for obese individuals in a singleton pregnancy [3]. To account for variable gestational weight gain at the time of delivery, methods adjusting for specific weight gain by gestational week of delivery to each class or pre-pregnancy BMI, as described in Woolfolk et al. were applied. The algorithm utilized IOM recommendation for weight gain per trimester, pre-pregnancy BMI and gestational age at delivery to determine the expected gestational weight gain at the time of delivery [22]. Using this approach to categorize gestational weight gain, individuals were classified as ‘below’, ‘met’, and ‘above’ IOM recommendations.

Bivariate analyses of maternal characteristics and COVID-19 exposure were performed using chi-square tests of association with two-category exposure and three-category variable based on gestational age at the start of the pandemic. Multinominal logistic regression modeling was used to examine the association between pandemic exposure, both dichotomized (≤20 weeks’ gestation at the start of the pandemic vs. pre pandemic) and categorical (<14 weeks’ gestation vs. 14–20 weeks’ gestation at the start of the pandemic vs. pre pandemic), with gestational weight gain categories using those who met recommendations as the reference group. Statistical analysis was performed using SAS version 9.4. This study was approved by the Yale University Institutional Review Board with waiver of informed consent.

Results

A total of 5,377 individuals met the inclusion criteria. 67.3 % (n=3,619) were in the pre-pandemic group and 32.7 % (n=1,758) in the pandemic group. Most individuals in the study (42.0 %; n=2,256) had a pre-pregnancy BMI classified as normal. A small percentage (0.7 %; n=36) of individuals had a BMI classified as underweight, 27.3 % (n=1,467) had a BMI classified as overweight, and 28.9 % (n=1,554) had a BMI classified as obese, according to WHO criteria [19].

No significant differences were observed in baseline characteristics between the pre-pandemic and early pandemic groups as noted in Table 1 with the exception of hypertensive disorders in pregnancy and frequency of nutrition encounters in pregnancy. Regarding hypertensive disorders category, the percentage of chronic hypertensive disorders alone was higher in the pandemic group (5.8 %, n=102) vs. (3.8 %, n=136); p=0.03. The percentage of individuals with hypertensive disorders of pregnancy alone without pre-existing chronic hypertension was higher in the pandemic group, 15.5 % (n=273) vs. 14.3 % (n=519). The percentage of patients with chronic hypertension with superimposed hypertensive disorders of pregnancy was lower in the early pandemic group (4.8 %) compared to those in the pre-pandemic (5.8 %) period. This trend reverses however with regard to nutritional counseling where more early pandemic patients had documented counselling (12.8 %) compared to those in the pre-pandemic period (9.7 %).

In the study population, 17.4 % (n=934) of individuals were classified as below recommended gestational weight gain, 23.8 % (n=1,280) met recommendations and 58.8 % (n=3,176) exceeded recommendations for gestational weight gain based on their pre-pregnancy BMI and gestational age at delivery. The percentage of individuals that were classified as having above recommended gestational weight gain were similar in the pre-pandemic (58.8 %, n=2,127) and post-pandemic (58.9 %, n=1,036) groups (Table 2). Only about a quarter of individuals in each epoch met gestational weight gain recommendations (24 %, n=870) in the pre-pandemic group and (23.3 %, n=410) in the pandemic group. Individuals who met below recommended gestational weight gain were also similar, with 17.2 % (n=622) in the pre-pandemic group vs. 17.8 % (n=317) in the pandemic group. There were no statistical differences (p=0.78) between the pre-pandemic vs. pandemic group in individuals who met, exceeded, or were below recommended gestational weight gain.

Compared to the pre-pandemic epoch individuals in the pandemic period did not experience weight gain below (OR 1.06, 95 % Cl 0.89–1.27) or above (OR 1.03, 95 % Cl 0.89–1.19) IOM weight gain recommendations, respectively (Table 3). When the pandemic group was stratified by gestational age, the individuals less than 14 weeks’ gestation did not experience a difference in weight again below (OR 1.18, 95 % Cl 0.95–1.45) or above (OR 1.1, 95 % Cl 0.94–1.31) the IOM recommendations. Similarly, individuals who were between 14 and ≤20 week’ gestation did not experience a difference in weight gain below (0.89, 95 % CI 0.68–1.16) or above (0.92, 95 % CI 0.75–1.13) the IOM recommendations.

Discussion

Conclusions

This study demonstrates no significant difference in meeting recommended maternal weight gain before and during the COVID-19 pandemic. Similarly, duration spent in the early COVID-19 pandemic did not demonstrate a significant difference in gestational weight gain. Further studies are needed to assess how activity levels and dietary habits may have been altered during the pandemic period. In general, most individuals in our population exceeded IOM recommendations for weight gain in pregnancy based on pre-pregnancy BMI, especially when compared to the national average, and should be an area of focus for improvement of care.