Background: Appropriate gestational weight gain (GWG) is important for optimal pregnancy outcomes. This study prospectively evaluated the associations between GWG during the second and third trimesters of pregnancy and adverse pregnancy outcomes in an urban Tanzanian pregnancy cohort.
Methods: We used data from a randomized clinical trial conducted among pregnant women recruited by 27 weeks of gestation in Dar es Salaam, Tanzania (N = 1230). Women's gestational weight was measured at baseline and at monthly antenatal visits. Weekly GWG rate during the second and third trimesters was calculated and characterized as inadequate, adequate, or excessive, in conjunction with measured or imputed early-pregnancy BMI status according to the 2009 Institute of Medicine (IOM) GWG guidelines. We used multivariable Poisson regression with a sandwich variance estimator to calculate risk ratios (RR) for associations of GWG with low birth weight, preterm birth, small for gestational age (SGA), and large for gestational age (LGA). Degree of appropriate GWG defined using additional metrics (i.e., percentage of adequacy, z-score) and potential effect modification by maternal BMI were additionally evaluated.
Results: According to the IOM guidelines, 517 (42.0%), 270 (22.0%), and 443 (36.0%) women were characterized as having inadequate, adequate, and excessive GWG, respectively. Overall, compared to women with adequate GWG, women with inadequate GWG had a lower risk of LGA births (RR = 0.54, 95% CI: 0.36-0.80) and a higher risk of SGA births (RR = 1.32, 95% CI: 0.95-1.81). Women with inadequate GWG as defined by percentage of GWG adequacy had a higher risk of LBW (OR = 1.93, 95% CI: 1.03-3.63). In stratified analyses by early-pregnancy BMI, excessive GWG among women with normal BMI was associated with a higher risk of preterm birth (RR = 1.59, 95% CI: 1.03-2.44).
Conclusions: A comparatively high percentage of excessive GWG was observed among healthy pregnant women in Tanzania. Both inadequate and excessive GWGs were associated with elevated risks of poor pregnancy outcomes. Future studies among diverse SSA populations are warranted to confirm our findings, and clinical recommendations on optimal GWG should be developed to promote healthy GWG in SSA settings.
Trial registration: This trial was registered as "Prenatal Iron Supplements: Safety and Efficacy in Tanzania" (NCT01119612; http://clinicaltrials.gov/show/NCT01119612 ).
Keywords: Adverse birth outcomes; Gestational weight gain; Institute of Medicine (U.S.); Tanzania.
Pregnancy is a critical lifetime event for both mother and the offspring, with implications in short-term and long-term health consequences. Gestational weight gain (GWG) is an important modifiable factor for pregnancy outcomes related to infant body size and weight and prematurity. Countries in sub-Saharan Africa (SSA) have long had poor rates of insufficient GWG and pregnancy complications associated with insufficient GWG. Nevertheless, some SSA countries are experiencing economic transitions accompanied with changes in lifestyle and nutrition, which might impact pregnancy experiences, including GWG and pregnancy outcomes. This study aimed to characterize recent GWG patterns and the associations of both inadequate and excessive GWG with adverse pregnancy outcomes, using an urban pregnancy cohort in Tanzania. This study found that 42.0%. 22.0%, and 36.0% of women had insufficient, adequate, and excessive GWG, respectively. Insufficient GWG was associated with higher risks of small infant size and low infant body weight, and excessive GWG was associated with higher risk of preterm birth, particularly among women with body mass index 18.5–25.0 kg/m2. Results from the present study highlight that both insufficient and excessive GWG are of potential public health concerns in urban centers of SSA, concerning upward trends in obesity and possibly obesity-related pregnancy consequences. Local public health practitioners should continue to advocate longitudinal GWG monitoring and care among African pregnant women, and optimal GWG with feasible and effective clinical guidelines should be developed to prevent both over- and under-gaining of maternal weight during pregnancy.
© 2022. The Author(s).