Babies born through cesarean deliveries are 15% more likely than babies born through vaginal delivery to grow up as obese beings, says a prospective cohort study led by experts from Harvard T H Chan School of Public Health. Upon comparing siblings born from vaginal birth and cesarean delivery, those born through cesarean delivery were 64% more prone to becoming obese.

In cases of multiple deliveries, it was also recorded by the researchers that the individuals born via vaginal birth to mothers, who had previously undergone a cesarean deliveries, had a reduced rate of 31% to become obese as they grow up.

Medical experts have always preferred vaginal birth over birth through cesarean section until they foresee a complication in prenatal tests. This long held preference is further validated by this study which was also published recently in JAMA Pediatrics.

Carried out from 1996 to 2012, the participants of the Growing Up Today Study included 22,068 offspring born to 15,271 participated through responding to the follow-up questionnaires which stretched from ages of 9 to 14 and ages of 20 to 28 years. While the study results also had many confounding factors which had contributed to the obesity risks, the final results were adjusted to give a fair comparison.

The confounding factors identified and adjusted in this study included mother’s pre-pregnancy BMI, age at delivery, smoking status, previous cesarean deliveries and origin of these women.

Although the researchers are still building on evidence which is leading to this stark difference in obesity rates in children, it is likely that the reason behind this is the baby’s exposure to mother’s gastrointestinal microbiota at the time of birth. The children born through vaginal deliveries have a greater exposure to the mother’s vaginal and gastrointestinal microbiota.

On the contrary, the children delivered through cesarean procedure are only exposed to mother’s skin microbiota and external bacteria at the time of birth. It is speculated that as these children are deprived of these beneficial bacteria, their metabolism, appetite patterns and digestion may be different from their counterpart.

In addition to this, it was also found that the children born from cesarean delivery harbor more staphylococci and few bilidobacteria which has an underlying connection with the energy harvesting capacity and risk of becoming obese later in life.

The trend of C-section births is on the rise, and contributes to over 32% births in the US alone. This figure translates into 1.3 million cesarean procedures being performed per anum in the US. However, efforts are being carried out to shift the paradigm of delivery mode preference amongst people.

Inspite of the fact that cesarean section can be life savior in many situations, a stigma of increased health risks remains attached to it. The mere idea of cutting a section through the belly to get out the baby is appalling to many, while others fear post-operative health complications.

In this context, senior author of the study and associate professor of nutrition and epidemiology at Harvard Chan School, Jorge Chavarro said, “Cesarean deliveries are without a doubt a necessary and lifesaving procedure in many cases. But cesareans also have some known risks to the mother and the newborn. Our findings show that the risk of obesity in the offspring could be another factor to consider.”

Previously conducted studies have also suggested that the risk rate of maternal morbidity and post-birth complications are manifold higher in cesarean deliveries when compared with vaginal deliveries. The most commonly associated risks following cesarean deliveries are rates of maternal transfusion, ICU admissions, ruptured uterus and unplanned hysterectomy (removal of uterus).

The Centers for Disease Control and Prevention (CDC) found out that the risks of these complications stayed consistent for women of all ages, races and ethnicities. The need of maternal blood transfusion was 525.1 per 100,000 deliveries higher for cesarean deliveries in comparison with vaginal deliveries and ICU admissions rate was 383.1 per 100,000 deliveries higher in cesarean deliveries. Similarly, on average 100,000 births, the rate of ruptured uterus was 88.9 and unplanned hysterectomy was 143.1 in cesarean deliveries.

The risk rates of ruptured uterus were found to be higher in women who undergo repeated C-section surgeries which lead to this condition marked by a tear in the uterine wall, often due to repeated incisions made during multiple c-section procedures.

Although it is a rare condition, it can put the fetus and mother at life-threatening risks which include fetal distress, maternal hemorrhage resulted from premature separation of the placenta or a prolapsed umbilical cord (which can trap against the baby’s body at the time of delivery) or postoperative infections.

Furthermore, the risk of unplanned hysterectomy leads to future infertility. It was, however, also observed that women who preferred vaginal birth after cesarean birth (VBAC) had a low risk rate for these four morbidities.

However, under certain complicated pregnancy cases, undergoing a cesarean delivery becomes inevitable. Few of such conditions include twin or multiple pregnancies, problems with the position of placenta, cervix or umbilical cord.

In addition to this, it becomes necessary if the baby’s position is either breech or transverse, if the baby is getting adequate oxygen supply and at a risk of being born still, if the cervix isn’t opening despite strong labor contractions, or if the mother suffers from a health condition such as heart problem, hypertension or infections that can pass onto the child across the placenta.

With this study, a significant link of C-section deliveries and child obesity has emerged which in itself in a great point of concern for authorities. While CDC recorded in 2014 that a third of children and adolescents were obese which is an open invitation to variety of health conditions, the statistics continue to rise. In future, however, it is hoped that better understanding of obesity, association with mode of birth and role of gut bacteria will be established to combat this global health problem.