Objective: Institute of Medicine (IOM) gestational weight gain (GWG) guidelines are commonly used worldwide. Whilst comprehensively developed, they are not underpinned by systematic review or meta-analysis, lack ethnic diversity and are not informed by the most contemporary maternal data. This is relevant as obesity rates and rising GWG are well documented. Here we complete a systematic review, meta-analysis and meta-regression to evaluate the 2009 IOM guidelines in contemporary maternal populations across all weight categories and broad ethnic groups.
Method: EMBASE, All EBM Reviews, Medline and Medline in-process were searched in Ovid from 1st January 1999-28th January 2016. Methodological quality was assessed. Primary outcomes were preterm birth, small for gestational age and large for gestational age. Secondary outcomes were caesarean section, macrosomia and gestational diabetes. Thirty authors were contacted for additional information or request for reanalysis given the heterogeneity of published data. Nineteen cohort studies were included.
Results: In 1,137,461 women, GWG was below, at or above guidelines in 20, 29 and 51% of pregnancies respectively. GWG below recommended had higher SGA [odds ratio (OR) 1.50, 95% CI 1.39, 1.62] and preterm birth (OR 1.37, CI 1.21, 1.55), and lower LGA (OR 0.62, CI 0.57, 0.67) and macrosomia (OR 0.65, CI 0.57, 0.73) compared to recommended GWG. GWG above recommended had lower SGA (OR 0.65, CI 0.62, 0.68) and preterm birth (OR 0.77, CI 0.68, 0.88) and higher LGA (OR 1.90, CI 1.79, 2.01), macrosomia (OR 1.83, CI 1.69, 1.99) and caesarean (OR 1.29, CI 1.24, 1.35). Subgroup analyses stratified by obesity class I-III, found similar risks for LGA, SGA, caesarean and macrosomia.
Conclusions: In this review over 1,000,000 pregnancies in a contemporary population with high mean BMI and diverse ethnicity, we advance knowledge by demonstrating that GWG outside 2009 IOM recommendations is associated with greater maternal and infant adverse effects. This work attests the value of the 2009 IOM guidelines and highlights the need to implement GWG recommendations broadly across maternity care.