Size difference in IVF babies disappears by adulthood

THE “IVF effect”, in which children born using assisted reproduction are smaller and lighter, disappears by the time they become adults, scientists have found.

A study by the University of Bristol which looked at 158,000 children born through assisted reproductive technology (ART) found differences in growth and weight are no longer apparent by late adolescence.

Since the first birth of a child conceived by in vitro fertilisation (IVF) in the late 1970s, questions have been raised about the risks to children conceived this way.

About one in seven couples have difficulty conceiving in Britain, leading to around 53,000 patients a year having fertility treatment.

Peter Thompson, chief executive of the Human Fertilisation and Embryology Authority, said: “The findings will come as a welcome relief to patients who begin treatment in the hope of one day having healthy children of their own.”

Just over one in 30 children are conceived by ART, on average one child in each primary school class.

Previous studies have shown an increased risk of low birth weight and pre-term birth in offspring conceived artificially but little is known about long-term growth and weight gain. The team found that those conceived using ART were on average shorter, lighter, and thinner from infancy up to early adolescence compared with their naturally conceived peers. But the differences became smaller with age.

Dr Ahmed Elhakeem, senior research associate in epidemiology at Bristol Medical School, said: “This is important work. Over the last three decades conception by ART has increased. Since the first birth of a child by IVF, concerns have been raised about the risks to the children conceived.

“Parents and their children conceived by ART can be reassured that this might mean they are a little bit smaller and lighter from infancy to adolescence, but these differences are unlikely to have any health implications, “he added.

The first baby conceived through IVF was Louise Brown, who was born at Oldham and District General Hospital in Manchester on July 25 1978.

Since then, more than eight million babies around the world have been born through IVF.

The researchers called for more work looking at the longer-term impact of artificial birth on heart and metabolic issues.

The study was published in the journal