Scientists discovered gene variants that increase the risk of excessive weight gain in women during pregnancy, which is directly associated with excessive weight in newborns.
The findings of the study, “MC4R and ENPP1 gene polymorphisms and their implication in maternal and neonatal risk for obesity,” were published in Scientific Reports.
Women with a normal body mass index (18.5 to 24.9 kg/m2) are expected to put on between 11.5 and 16 kg (about 25 to 35 lbs.) during pregnancy. When pregnancy weight gain exceeds these limits, a series of complications can affect both the mother and the unborn baby.
Such maternal weight gain is also accompanied by “modifications of neonatal birth weight (BW) with afterwards consequences on their evolution, such as macrosomia [large body size] and obesity, and a wide range of other complications, like cardiovascular diseases, muscular and skeletal impairment, type 2 diabetes mellitus, and even psychological consequences,” they added.
Several genes have been reported to play a role in the development of obesity. Some recent studies also suggest that several melanocortin receptor (MCR) genes (MC4R, MC3R, MC2R) and the nucleotide pyrophosphatase/phosphodiesterase (ENPP1) gene also play key roles in the disease.
Scientists with the University of Medicine, Pharmacy, Sciences and Technology in Romania set out to investigate the impact of two gene variants — one from MC4R (rs17782313) and the other from ENPP1 (rs1044498) — on women’s gestational weight gain (GWG) and newborn birth weight (BW).
The cross-sectional study enrolled 185 mothers and their newborns. Mothers were divided into two groups: a control group that included 134 underweight or normal-weight women, who had a BMI lower than 25 kg/m2; and an experimental group that included 51 overweight or obese women with a BMI greater than 25 kg/m2.
Demographic data, body measurements, body composition, and genetic parameters were assessed in all study participants.
Analyses revealed a direct association between the women’s initial BMI and GWG, with more women in the overweight/obese group putting on excessive weight during pregnancy compared to those in the control group (72.5% vs. 59%).
Further analyses showed that both gene variants were linked to an increased risk of excessive body weight before pregnancy, but not to a greater risk of excessive weight gain during pregnancy.
However, they found that babies whose mothers had gained too much weight while pregnant were born with excessive weight. Besides being directly correlated with GWG, a newborn’s BW was also linked to gestational age, presence of the rs1044498 ENPP1 gene variant, and the mother’s smoking status during pregnancy.
Newborns with higher middle upper arm circumference (MUAC) values also tended to have the normal version of the rs17782313 MC4R gene variant, the study noted.
“Our study pointed out the role of MC4R rs17782313 and ENPP1 rs1044498 in maternal and neonatal obesity risk in correlation with BMI … which could be useful for diagnosing obesity in mother-newborn couples,” the researchers wrote.