Gestational Weight Gain and Severe Maternal Morbidity at Delivery Hospitalization

The recent article by Platner et al¹ in the March 2019 issue examines whether gestational weight gain outside Institute of Medicine (IOM, now known as the National Academy of Medicine) recommendations is associated with severe maternal morbidity. We commend the investigators for recognizing the importance of considering gestational age in studies of total gestational weight gain and for their acknowledgment that the IOM guidelines were developed for full-term pregnancies. However, by restricting their analysis to gestational durations of 37–45 weeks, they likely removed numerous women with severe maternal morbidity, reducing the generalizability of their results. In California, approximately one quarter of women with severe maternal morbidity deliver before 37 weeks of gestation. Additionally, analyzing term pregnancies as a single group does not address the possible contribution of increasing weight gain after 37 weeks. Two alternative analytical approaches that help disentangle gestational duration from weight gain could remedy these limitations. Both allow inclusion of all eligible births. Most simply, researchers can adjust for gestational duration. Alternatively, researchers can convert weight gain to z-scores using charts specific to prepregnancy body mass index group and gestational duration, as described in detail elsewhere.² It is also important to determine whether results differ after excluding women with conditions that increase weight gain, particularly preeclampsia and certain heart diagnoses. We encourage those researching severe maternal morbidity and related perinatal outcomes to consider using these methods. We would be very interested to see how applying these approaches affects the findings reported by Platner et al.¹