Are firstborns more likely to be born late?
We all know that babies don’t always arrive on schedule and mums often think that firstborn babies are often late but is there any research to back it up or is it just an old wives tale?
It has been reported on the Livescience website that, Allen Downey, a professor of computer science at Franklin W. Olin College of Engineering in Massachusetts carried out a study to find out just that.
He studied a 2002 Centers for Disease Control and Prevention survey of 7,643 women, who reported 9,148 live births.
He found that first babies were, indeed, slightly more likely to be born late, at 41 weeks or later, compared with other babies.
According to Downey, a firstborn baby has a 15-16 per cent chance of being born late, compared with a 9-10 per cent chance for other babies. Also, his results showed that most babies were born at 39 weeks of pregnancy.
However, the study also found that firstborns were also more likely to be born early, at 37 weeks or earlier.
In essence, firstborn babies are less likely to be born on time. Downey puts this down to the fact that the conception date may not be accurate.
The Livescience website goes on to report that Dr. Jill Rabin, chief of ambulatory care, obstetrics and gynecology at Long Island Jewish Medical Center in New York said that a baby’s due date is an estimate, and it’s normal for babies to arrive two weeks before or after that day.
She said: “When you’re expecting a first baby…you’re locked on to the due date, and you expect the baby on that due date,
“It still can be two weeks high or low, and it’s considered normal,” she added.
Rabin said there is no known biological reason why firstborn babies would be more likely to be early or late.