A pregnant woman has her blood pressure measured by a hospital staff
A pregnant woman has her blood pressure measured by a paramedic after she and colleagues were evacuated following an earthquake in Mexico City April 18, 2014. The magnitude 7.2 quake was centred in the south-western state of Guerrero, close to the Pacific beach resort of Acapulco, the U.S. Geological Survey (USGS) said. Some residents of the capital ran outdoors in their pajamas after the quake. Electricity was cut off in parts of the city and some residents said paintings fell off the walls while small parts of masonry crumbled inside apartment buildings. REUTERS/Bernardo Montoya REUTERS/Bernardo Montoya

A study printed in the journal Pediatrics found that children whose mothers were obese during their pregnancy are at an increased risk of developing asthma than children who have normal weight mothers. The children of mothers who were overweight are at 20 to 30 percent higher odds of asthma.

"These results included studies that evaluated asthma at different time points in childhood, from a little over a year of age all the way to 16 years of age," said assistant professor of pediatrics at Children's Hospital of Pittsburgh and lead researcher Dr. Erick Forno. Several researches conducted in the past were analysed as a part of the review but a clear association between mother's weight in pregnancy and her child's risk of asthma was not able to be proved. 14 reports that analysed 100,000 mother child pairs were studied as a part of the research.

Frono said that the link between the two remained unclear and that the studies they investigated did not evaluate the mechanisms involved in this association, so the link between the two is still unknown.

He explained that several factors may play a role, "We know for example that obesity sometimes leads to inflammation that can contribute to diabetes or heart disease, and perhaps this inflammation in the mother somehow affects the developing lungs and airways in the baby." He also stated that there may be certain nutrients that mothers with healthier diets may consume that would protect her child from asthma.

"Another mechanism may be that certain factors in the genetic make-up of the mother predisposes both to obesity (in herself) and to asthma (in her child). Most likely there is a combination of all these playing a role," Forno suggested.

Forno suggested all women who want to get pregnant must maintain a healthy weight and a healthy diet. It would avail more benefits than just decreasing the risk of asthma in the child. Women who are overweight during pregnancy will have children with a 36 percent higher risk of having asthma. The study suggests that if the women do not have a history of asthma their influence on the child's development of asthma as he grows will be more.

Dr. David Mendez, a neonatologist at Miami Children's Hospital, said that the study asks a question that only additional research can answer. Such research would have to probe into several other factors like the mother's history of asthma and the baby's exposure to cigarette smoke. He also informed that such a study would take years to complete as it would have to wait for the children to grow up. Menzes was not involved with the study.

Being overweight has several disadvantages both for the mother and the baby, it could cause pre-term caesarean deliveries and can impact the child's birth weight as well resulting in low-birth-weight infants.