14 DAY TRIAL // Canadian scientists made a new study on the link between overweight and obese mothers and the risk of preterm births. The results show that normal weight women have less chances of giving birth before 37 weeks and having an overweight newborn. The study was published yesterday on bmj.com.
For the research, the team took into consideration the results of 84 previous studies and established the effects of mothers' weight on preterm birth and low birth weight (under 2500kg); women included in the studies gave birth to a single baby, and came from developed or developing countries.
Their results were that overall there were no significant differences between normal weight and overweight women. Still, after accounting for publication bias, a 30% increased risk of induced preterm birth before 37 weeks in overweight and obese women appeared. As the woman's weight increases, so does the risk of induced preterm birth before 37 weeks, highly obese women reaching an amazing 70% greater risk than normal weight mothers. Another risk that was related to overweight in mothers was early preterm – before 33 weeks. In very obese women the percentage reached 82%.
Scientists noticed that the publication bias changed the first tendency noticed, for women overweight or obese to have a lower risk of giving birth to a low weight baby, compared to normal weight mothers, particularly in developing countries. The study's authors warn that doctors should be aware that overweight or obesity does not protect against low birth weight, and they should consider close observation in these cases.
Most common pregnancy complications are due to overweight and obesity nowadays. Statistics say that in the UK, 33% or pregnant women are overweight or obese and in the US, between 12 and 38 percent of pregnant women are overweight and 11% to 40% are obese. In India, pregnant women are 26% overweight and 8% obese and, finally, in China 16 percent of pregnant women are either overweight or obese.
Low birth weight and preterm birth are the most common causes of deaths among newborns and childhood illness. Researchers advise future mothers to have counseling before pregnancy and to try to reduce their weight. Overweight women should be followed by a specialist on a regular basis, during their pregnancy.