According to a study published in the open-access journal PLOS Medicine, both fathers' and mothers' mental histories are related to premature birth.

The study demonstrates for the first time that the risk of preterm birth is higher in infants whose fathers or mothers have psychiatric disorders than in those who do not, and the risk is enhanced further when both parents have been diagnosed.

Preterm birth is associated with negative health consequences for infants. Women with psychiatric diagnoses are at increased risk of preterm birth, but less is known about the risk in offspring of fathers with psychiatric diagnoses and for couples where both parents had psychiatric diagnoses.

Weiyao Yin and colleagues from the Karolinska Institutet analysed data on all live births to Nordic parents in Sweden between 1997 and 2016.

They obtained psychiatric diagnoses from the National Patient Register and data on gestational age from the Medical Birth Register.
There were 1.5 million births in the cohort, of which 15% were born to parents with a diagnosis.

The team observed a trend towards earlier gestational age in the offspring of parents with psychiatric disorders. For parents without a diagnosis, 5.8% of babies were born preterm.

A paternal diagnosis increased the risk to 6.3% of births and a maternal diagnosis increased the risk to 7.3% of births. However, where both parents had a diagnosis, the risk of preterm birth was greatest, affecting 8.3% of births.

The researchers also found that the risk was further increased for parents mothers as well as fathers with several co-existing psychiatric disorders.

Future studies should examine whether additional social support and prenatal care for families with a positive psychiatric history could have an impact on gestational age.

Yin adds, “Children of parents with mental illness are at increased risk of being born too early – both the mothers’ and fathers’ are important.”