PREGNANT women battling eating disorders are up to 70 per cent more likely to have premature babies, research suggests.
Data from 1.2million mothers also found their babies were also more likely to have a small head circumference, known as microcephaly.
Experts blamed the nutritional deficiencies and soaring stress hormones associated with eating disorders for the babies’ growth problems.
Doctors behind the study said mothers-to-be with anorexia and bulimia should have more frequent screenings during pregnancy.
Eating disorders affect millions of people around the world, the majority of whom are women of adolescent or childbearing age.
It’s already known disordered eating habits can cause poor development, premature birth, low birth weight, respiratory distress, and more. But studies have been relatively small.
The Karolinska Institutet research, published in JAMA Psychiatry, looked at mothers who gave birth in Sweden between 2003 and 2014.
Nearly 2,800 had anorexia and 1,400 had bulimia. Some 3,400 had an unspecified eating disorder (ENDOS) which does not fit into a typical category.
The study showed that all types of eating disorders increased the risk of premature birth, microcephaly and hyperemesis during pregnancy, a severe form of nausea and vomiting affecting the mother.
Why do eating disorders affect an unborn baby?
The researchers noted several possible explanations for the findings.
The stress hormone cortisol tends to be high in women with anorexia and bulimia and has previously been linked with microcephaly.
Both stress and some nutritional deficiencies – which can be caused by a poor diet – in the mother have previously been connected to premature birth or restricted growth.
Vitamin and mineral deficiencies have also been linked to placental abruption, which could explain the increased risk of bleeding during pregnancy.
When it comes to hyperemesis, the researchers said the risk was lower when they adjusted for psychiatric conditions such as anxiety and depression, suggesting there are other issues at play.
There was a 60 per cent increased risk of preterm birth for women with anorexia, 30 per cent for bulimia and 40 per cent for ENDOS.
Women with ENDOS had a 70 per cent increased risk of very preterm birth.
Maternal anorexia was linked with an almost two-fold risk of having a baby with microcephaly. The risk was 60 per cent for bulimia and 40 per cent for ENDOS.
The risk of anemia was twice as high for women with active anorexia or ENDOS than for mothers without eating disorders.
Active anorexia was also associated with an increased risk of antepartum hemorrhage – bleeding from the genital tract from 24 weeks onwards.
The prevalence of complications was higher if the women was still battling an eating disorder at the time of carrying her baby.
But those who had previously been diagnosed – defined as more than a year before becoming pregnant – were still at a higher risk of complications compared to mothers who had never been diagnosed with an eating disorder.
‘Women with eating disorder should be recognized as a high-risk group among pregnant women,’ said co-author of the study, Dr Ängla Mantel.
‘From a clinical point of view, this means that care providers need to develop better routines to identify women with active or previous eating disorders and consider extended pregnancy screenings to meet their needs.’
Other outcomes remained largely the same after adjustment for variables such as age, smoking and birth year.