Miscarriage and abortion were also linked to a 70 per cent increased risk of having a pre-term birth.
The findings come from a population-based study of over 45,500 mothers giving birth in the USA between 1959 and 1966. Around 11 per cent had low birthweight (below 2,500g) infants,
6 per cent low birthweight infants delivered at term and 14 per cent preterm births.
Logistic regression showed that women who reported one miscarriage or abortion in the past were three times as likely to have a low birthweight baby as those who had no such history. This risk increased to five-fold in women who had two previous abortions or miscarriages, and to nine-fold in women who had a history of three abortions or miscarriages.
Similarly, women with one previous abortion or miscarriage were 70 per cent more likely to have a pre-term birth. This risk increased to two-fold in women with a history of two abortions or miscarriages and three-fold in those with three of these past events.
The reasons for the association remain unclear, especially as the researchers were unable to differentiate between abortion and miscarriage in the study data. But women and healthcare professionals must be aware of this potential risk, say the researchers from Virginia Commonwealth University.
rachel.liddle@haymarket.com
Journal of Epidemiology and Community Health
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