A recent study of almost 2 million births found a strong link between a mother’s weight at delivery and the health of her newborn. Babies born to mothers who were overweight or obese at the time of delivery faced much higher odds of suffering from asphyxia, meconium aspiration, or having seizures than newborns with mothers of healthy weight.

The incidence of oxygen deprivation (asphyxia) at birth rose in correlation to mother’s body mass index (BMI), according to the study’s findings. Dr. Martina Persson led the study, conducted at the Karolinska Institutet, a medical university in Solna, Sweden, that is widely regarded as one of the most prestigious medical universities in Europe, as well as one of Europe’s largest.

Persson and her research team examined the medical records of 1,764,403 live singleton births in Sweden between 1992 and 2010. All babies were delivered at full term, during week 37 or later. Medical data from the Swedish Medical Birth Register (MBR) were used in the study. The MBR tracks the progression of pregnancy beginning with the first prenatal visit until after childbirth. Data includes maternal health, including weight and BMI, as well as a neonate’s (newborn’s) Apgar scores at 1, 5, and 10 minutes. Complications of delivery, such as asphyxia and seizure, are also documented in the MBR.

A baby’s first bowel movement (meconium) usually occurs within 12 hours after birth. When the meconium is expelled during delivery, it signals neonatal distress. Inhalation of this waste material during the birthing process can cause breathing difficulties.

Apgar scores measure five points of health — heart rate, respiratory effort, muscle tone, response to stimulation, and skin color (healthy color versus grey or blue, which signals oxygen deprivation) — in the moments after birth. Ten is the highest score possible but scores of 7 or higher signal good health. A score 3 or lower is cause for alarm.

Persson used weight categories issued by the World Health Organization:

  • BMI 18.5 or lower = underweight
  • BMI 18.5 to 24.9 = normal weight
  • BMI 25 to 29.9 = overweight
  • BMI 30 to 34.9 = grade I obesity
  • BMI 35 to 39.9 = grade II obesity
  • BMI 40 or higher = grade III obesity

At 5 minutes after birth, low Apgar scores (0 to 3) were noted in 1,380 babies (0.8 per 1,000). At 10 minutes, low scores were still observed in 894 babies (0.5 per 1,000). The largest number of babies with low scores were born to mothers of normal weight but the proportion for low scores was highest in women of excess weight. The risk of asphyxiation at five minutes was closely related to mother’s BMI, too:

  • 57% greater risk of neonatal asphyxiation when mother’s BMI was 25 to 29.9
  • Two times greater risk when BMI was 30 to 34.9
  • Three times the risk when BMI was 40+

The baby’s risk of seizure and meconium aspiration was greater when the mother was overweight or obese than for babies born to women of normal weight.

The global obesity epidemic affects the health of the person carrying excess weight but the Persson study highlights its impact on the children born to overweight women, too. Persson urges women to maintain optimum weight during reproductive years so babies can have the healthiest start possible.

Source: Perrson, Martina, et al. “Maternal Overweight and Obesity and Risks of Severe Birth-Asphyxia-Related Complications in Term Infants: A Population-Based Cohort Study in Sweden.” PLOS / Medicine. PLOS. May 20, 2014. Web. Jun 11, 2014.