The impact of gestational weight loss on maternal and neonatal outcomes
- Correspondence to Deborah K Steward
College of Nursing, The Ohio State University, 1585 Neil Avenue, Columbus, OH 43210, USA;
Implications for nursing practice and research
The results of this study suggest there is a need to:
■ Monitor women's prepregnant body mass index (BMI).
■ Educate pregnant women about the importance of appropriate weight gain.
■ Prospective studies are needed to identify those factors that impact on gestational weight gain.
■ Longitudinal studies are needed to follow the developmental trajectories of children born to mothers who experience gestational weight loss.
There is a need to define what constitutes adequate weight gain during pregnancy. Paramount to this discussion is the effect of weight gain or loss not only on maternal health but also on the child's short- and long-term health. This is particularly important because of the increasing numbers of pregnant women who are obese; approximately one in five women are obese at the time of their pregnancy.1
Researchers who have examined weight gain in obese pregnant women have focused on maternal outcomes such as pre-eclampsia and the need for a caesarean delivery.2 Neonatal outcomes examined have included extremes of birthweight including large for gestational age (LGA) and small for gestational age (SGA).2 3 There is some evidence available to suggest that minimal weight gain or actual weight loss among obese women has no negative impact on maternal and neonatal outcomes.4 However, the available evidence is insufficient to develop guidelines at this time or to recommend minimal weight gain as an effective strategy for pregnant women.
Beyerlein et al conducted a retrospective analysis of a national obstetric dataset to determine the prevalence of gestational weight loss (GWL) in a sample of pregnant women (n=709 535). They also examined the effect of GWL on selected pregnancy-related maternal and neonatal outcomes. Data were examined for all singleton births between 2000 and 2007. Women were divided into six groups based on their BMI at the time of their first prenatal appointment. The groups included underweight, normal weight, overweight, obese class I, obese class II and obese class III. To address the effect of GWL on maternal and neonatal outcomes, the sample comprised of 445 323 women. Women with excessive weight gain were excluded from this analysis because excessive weight gain is associated with the development of adverse pregnancy outcomes. The sample was divided into two groups: mothers with weight loss and mothers who gained weight, and then stratified by BMI. The groups were compared on selected maternal and neonatal outcomes including pre-eclampsia, non-elective caesarean section, preterm delivery, LGA, SGA and perinatal mortality.
The percentage of women with GWL increased as maternal BMI increased. The majority of women exhibited a weight loss of 1–5 kg. Mothers who were obese and experienced GWL were less likely to have pre-eclampsia or require caesarean section than those who gained weight. This effect was not seen in women who were of normal weight or overweight. Women with GWL were more likely to deliver a preterm infant than those who gained weight. Across all BMI groups, GWL resulted in infants who were SGA. Mothers who gained weight were more likely to have an infant who was LGA. Perinatal mortality was not significantly different across BMI groups when preterm delivery was statistically controlled. The authors concluded that, although GWL was associated with lower risk of pregnancy complications, this was outweighed by an increased risk for adverse neonatal outcomes.
The findings of this study are important for several reasons and are consistent with the findings of other studies.2 3 The researchers are one of the few groups to focus specifically on GWL and include women who are normal weight and obese. The findings about neonatal outcomes are particularly important. It is well established that neonates who are SGA are at increased risk for long-term alterations in growth and development. It is also unclear whether GWL will have lasting physiological and metabolic consequences for children.2 Since GWL appears to increase the numbers of preterm deliveries, this has important consequences for neonatal outcomes. Numerous long-term complications are associated with preterm births that can impact growth and neurodevelopment. The presence of GWL in pregnant women requires further research to understand the impact on the developing child.