Published: 21-07-2023 09:25 | Updated: 14-08-2023 14:51

Mental illness in fathers may increase the risk of preterm birth

Newborn in hospital bed
Photo: Getty Images.

Children of parents with mental illness are at increased risk of being born too early, especially if it is stress-related, and both the mother’s and the father’s mental health seem to be of importance. This is according to a register-based study from Karolinska Institutet published in PLOS Medicine.

In Sweden, about five percent of children are born too early, before 37 weeks of pregnancy, and this is associated with negative health consequences for the child. Previous research has shown that women with psychiatric diagnoses are at increased risk of preterm birth, but less is known about how this is affected by the father’s mental health.

Now, researchers at Karolinska Institutet in Sweden have investigated this association in a large register-based study including almost 1.5 million births.

Support for families with mental illness

The researcher Weiyao Yin.
Weiyao Yin. Photo: Private.

“We found an increased risk if the father had a psychiatric diagnosis, especially if the mother suffered from mental illness as well,” says Weiyao Yin, postdoctoral researcher at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet. “This suggests that social support and preventive prenatal care for families with a history of mental illness may decrease the risk of preterm birth.”

The study included all live births in Sweden between 1997 and 2016. The researchers obtained psychiatric diagnoses from the National Patient Register and data on gestational age from the Medical Birth Register.

15 percent of the children had at least one parent with a mental health disorder. Babies whose fathers had a psychiatric diagnosis had a 12 percent increased risk of being born preterm, whereas the risk increased by 31 percent if only the mothers had a psychiatric diagnosis.

Higher risk if it was stress-related

If both parents had a history of mental illness, the risk increased by 52 percent compared to when neither parent had a psychiatric diagnosis. The researchers also analysed specific diagnoses separately and found that stress-related disorders were associated with the highest risks of preterm birth.

The risk increased by 23 percent if only the father suffered from a stress-related disorder, 47 percent if only the mother had a stress-related diagnosis and 90 percent if both parents had a diagnosis.

Portrait of Sven Sandin.
Sven Sandin. Photo: Gunilla Sonnebring.

“We also found that the risk was further increased if the parents had several co-existing psychiatric disorders,” adds Dr Sven Sandin, who led the study from Karolinska Institutet. “However, since this was an observational study, no conclusions can be drawn about causality.”

The study was mainly financed by the Swedish Research Council. Coauthor Jonas F. Ludvigsson at Karolinska Institutet has coordinated a study on behalf of the Swedish IBD quality register (SWIBREG) that received funding from Janssen. He has also received financial support from MSD for a paper reviewing national healthcare registers in China.


Paternal and maternal psychiatric history and risk of preterm and early term birth: a nationwide study using Swedish registers”. Weiyao Yin, Jonas F. Ludvigsson, Ulrika Åden, Kari Risnes, Martina Persson, Abraham Reichenberg,  Michael E. Silverman, Eero Kajantie, Sven Sandin. PLOS Medicine, online 20 July 2023, doi: 10.1371/journal.pmed.1004256.