New Delhi: Supporting women of childbearing ages to maintain a healthy weight could reduce the risk of developing pregnancy complications such as hypertension, having C-section delivery, or birthing heavier babies, new international research published in BioMed Central (BMC) Medicine journal has found.

While previous studies have correlated mother’s weight with pregnancy complications, researchers said they have addressed previous confounding issues like education and lifestyle to identify clearer causal links between an increased maternal weight and developing complications while being pregnant.

The findings could be key to advising future policies and ensuring women of childbearing age live healthy lives, the team said.

“A lot of research has identified correlations between a mother’s weight and health conditions in pregnancy, but these can make it very difficult to determine what is cause and what is effect, creating a confusing picture for mothers, clinicians and healthcare workers.

“We used a range of more robust approaches, giving clear evidence of where the mother’s weight caused the health condition and where it did not,” explained Rachel Freathy, study author and associate professor at the University of Exeter, UK.

To better understand how mother’s weight influenced a wide range of pregnancy-related complications, the team of researchers combined data from 14 studies in Europe and North America.

Overall, they included the body mass indices (BMI) of more than 4 lakh mothers in their analysis. BMI is calculated by dividing one’s weight in kilograms by their height in metres squared (kg/m2). They employed three different methodologies, with different strengths and weaknesses, to improve the current evidence, they said.

“By comparing results from different methods that have different limitations we have more confidence when all three agree that we have the causal effect,” said the study’s corresponding author, Deborah Lawlor, professor of epidemiology, University of Bristol, UK.

The team also compared their results with those coming from correlating father’s BMI with the pregnancy complications.

If the results in mothers were truly causal, the researchers would not expect to see a correlation in fathers. If they did, then it suggested both mothers and fathers’ results are confounded, they said explaining their hypothesis. They also performed a genetic analyses, called Mendelian randomisation, which they said was unlikely to be affected by confounding.

The researchers found that a higher mother’s BMI impacted 14 out of 20 pregnancy complications they studied, such as the risk of high blood pressure in pregnancy, pre-eclampsia and pregnancy diabetes.

For example, they found that for every one kg/m2 increase in maternal BMI, there was a 10 per cent increased risk of pre-eclampsia, a pregnancy condition characterised by hypertension and fluid retention and albuminuria (excess protein in urine because of kidney malfunction).

Other complications the team investigated included those regarding delivery such as needing a caesarean section or induction of labour, giving birth to heavier babies and requiring neonatal intensive care admission.