Researchers determine whether pregnancy weight gain between pregnancies may cause adverse outcomes such as gestational diabetes, macrosomia, and caesarean sections.
The relationship between a high weight before pregnancy and maternal and neonatal complications such as gestational diabetes (GDM), cesarean section (CS), prematurity, and stillbirth have been well established. These outcomes are important to understand and address because they result in increases in health care costs by affecting women and their newborns.
Lack of research on the impact of weight gain between pregnancies
There has not been much research regarding the impact of pregnancy weight gain between pregnancies and its effects on the mother and the baby. Recently, Oteng-Ntim and colleagues measured how pregnancy weight gain affected the most prevalent outcomes including large-for-gestational-age babies (LGA), small-for-gestational-age babies (SGA), GDM, CS, and macrosomia.
A baby was considered LGA if their birth weight was greater or equal to the 90th percentile of all babies with the same gestational age. A baby was considered SGA if their birth weight was less than the 10th percentile of all babies with the same gestational age. A baby with a birth weight of more than 4000g was said to have macrosomia, and a diagnosis of GDM was given to women who experienced any degree of glucose tolerance with the onset of pregnancy.
This article, recently published in BMJ Open, is a meta-analysis including 11 studies from January 1990 to January 2017. One study was from Belgium, seven were from the USA, one from Sweden, and two were from Scotland. To reduce the possibility of confounding variables the researchers only included the first two successive pregnancies. Any studies that were restricted to women with previous diabetes mellitus diagnoses were also excluded.
Weight gain between pregnancies increased the risk of developing gestational diabetes, requiring caesarean delivery, and having larger babies
The researchers reported that gaining weight in between pregnancies results in an increased risk of developing gestational diabetes, requiring a cesarean section delivery, and babies that are large for gestational age.
A decrease in pregnancy weight gain was associated with a 33% reduction in LGA, while an increase in pregnancy weight gain was associated with a 43% higher risk of LGA. The only study that measured macrosomia demonstrated that a decrease in body mass index (BMI) had a reduced risk of macrosomia, and an increase in BMI resulted in higher risk of macrosomia. There was no association observed with a decrease in pregnancy weight gain and risk of cesarean sections.
Other outcomes such as preterm birth, perinatal death, and pre-eclampsia were unable to be included as part of this meta-analysis because there was a lack of quality studies linked to these outcomes. Some studies accounted for the interval between pregnancies and pregnancy weight gain, however, the effect of these should not be underestimated, and all future studies should account for the interval between pregnancies. Another limitation of this review was that the studies were from singleton births coming from high-income Western countries. This limits the data from being generalized to other low-income populations.
In conclusion, pregnancy weight gain between pregnancies increases the risk of gestational diabetes, cesarean section, and large-for-gestational-age babies, but lowers the risk of small-for-gestational-age babies. Weight reduction has been associated with increased risk of SGA but lowered risk of GDM and LGA.
Written by Kimberly Spencer B.Sc. (Hons)
Reference: Oteng-Ntim, E., Mononen, S., Sawicki, O., Seed, P., Bick, D., & Poston, L. (2018). Interpregnancy weight change and dverse pregnancy outcomes: a systematic review and meta-analysis. BMJ Open, 8(6), e018778. doi: 10.1136/bmjopen-2017-018778