Teenagers giving birth for the first time are not at increased risk of adverse pregnancy outcomes. However, those having second births run an almost threefold risk of premature delivery and stillbirth, concludes a study in this week's BMJ.
Researchers at Glasgow University identified over 110,000 non-smoking women, aged between 15 and 29 years, who gave birth for the first or second time between 1992 and 1998. Risks of adverse outcomes, such as low birth weight, premature birth, still birth, and emergency caesarean section were analysed for two age groups: women aged 15-19 and women aged 20-29. Factors, such as smoking, social deprivation, and previous abortions were taken into account.
They found that non-smoking women aged 15-19 having a first birth were not at higher risk of adverse pregnancy outcomes, compared with women aged 20-29. By contrast, second births among 15-19 year olds were associated with an almost threefold risk of extremely premature birth and stillbirth compared with older women.
These findings contradict previous studies, which suggested that first teenage births were associated with adverse pregnancy outcomes. However, these studies failed to account for important environmental factors such as maternal smoking, explain the authors. The current study is also the first to show clearly that teenagers having their second baby are at significantly increased risk of pregnancy complications. This appeared to be independent of environmental factors but further work will be required to confirm or refute a biological cause for these findings, they conclude.