Paternal depression linked to premature birth
"Depression in expectant fathers linked to premature births," The Independent reports. A Swedish study found a link between paternal depression occurring for the first time and an increased risk of very premature birth.
The study, which looked at 366,499 births, also confirmed that women with depression before or during pregnancy are more likely to have a premature birth (also known as a preterm birth).
However, the reasons for the association with depression are unclear. One theory for the link between premature birth and depression in women is that it may be caused by the treatment – antidepressants – rather than the illness.
Therefore, any effect of men having depression, the researchers suggest, may be more to do with the stressful effects that depression in a partner has on the pregnant woman.
This suggestion is supported by evidence that the risk of premature birth was absent in cases where the expectant father did not live with the mother.
The researchers also float the idea that antidepressants may have an effect on sperm, but conclude that this is unlikely.
A limitation of the study is that the diagnosis of depression was based on whether men were prescribed antidepressants. Antidepressants are also used for other conditions, such as anxiety disorders, so some of the diagnoses may have been incorrect.
Pregnancy can be a stressful time for both partners, so you shouldn’t feel guilty or ashamed if you do experience depression during this time. What is important is that you seek help by talking to your GP.
Where did the story come from?
The study was carried out by researchers from the Karolinska Institutet and Stockholm University, Sweden, and was funded by the Karolinksa Institutet. The study was published in the peer-reviewed journal BJOG: An international journal of obstetrics and gynaecology. It is published on an open-access basis, meaning it is free for anyone to read online.
The study was reported accurately in most of the UK media sources that covered it, although they did not point out a few weaknesses in the study that could make the results less reliable. For example, as mentioned, people were assumed to have depression if they were treated with antidepressants, although these are used for other conditions besides depression.
What kind of research was this?
This was a national cohort study, using data from the Medical Birth Register of Sweden. This type of study is good at finding links between factors – in this case, depression and preterm birth – but cannot prove that one causes the other.
What did the research involve?
Researchers used data from a big national registry to look at hundreds of thousands of births, including almost 17,000 preterm births. They used linked databases to see whether either parent had been treated for depression in the two years prior to conception or the first 24 weeks of the pregnancy.
After adjusting their figures to take account of other factors that could influence the results, the researchers looked for links between depression in either parent and preterm birth. They assumed people had depression if they'd been prescribed antidepressants, or if they had received any treatment for depression in or out of hospital.
Other factors taken into account included the following confounders:
- whether a woman had previously had a miscarriage or ectopic pregnancy
- her height and weight
- whether she smoked
- her age
- how many times she'd given birth
They also looked at pregnancy complications, including gestational diabetes and pre-eclampsia. For fathers, they considered age, years of education and household income.
The researchers checked their figures for the effects of previous pregnancy or birth problems, the effects of both partners having had depression, and the parents living together or apart. They looked separately at very early (22 to 31 weeks) and moderately early (32 to 36 weeks) births.
They also looked for differences between "new" episodes of depression (where someone had treatment for depression after a period of 12 months when they’d had no depression) or "recurrent" depression.
Finally, they calculated the effects of depression in both men and women, on the chances of very early and moderately early prematurity.
What were the basic results?
The study found that women with new episodes of depression had a 34% higher chance of a moderately preterm birth (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.22 to 1.46), which increased to 42% with repeat depression (OR 1.42, 95% CI 1.32 to 1.53). However, the link between depression in woman and very preterm births was small enough that it could be down to chance.
By contrast, new depression in men was linked to a 38% higher chance of very preterm birth (OR 1.38, 95% CI 1.04 to 1.83), but not to a moderately preterm birth. Repeat depression was not linked to preterm birth.
How did the researchers interpret the results?
The researchers concluded that "paternal depression around the time of conception and in early pregnancy can have an effect" on the mother and baby, and "can increase the risk of preterm birth". They suggest that this is because of the stress placed on the pregnant women if her partner is depressed, and the lack of social support she may get from a depressed partner. They suggest that paternal depression may also affect sperm quality, especially for very early birth.
They say that the lack of effect seen in men with repeated depression may mean that men who have had their depression recognised and treated before may place less stress on their partner than men with newly-recognised depression.
They point out the contrast in the results seen for men and women. Women with repeated depression had a stronger link with preterm birth, but only for moderately preterm deliveries. They say this suggests that the effect of treatment (antidepressants) may be more important than the effects of depression.
Conclusion
This study has found a link between depression in expectant fathers and an increased risk of preterm birth in their babies. It was based on large, independent sources of data, and the researchers adjusted their figures to take account of many factors that could have skewed the results.
However, it's worth noting a few uncertainties.
The main measure of depression was whether people took antidepressants. People take antidepressants for many reasons, including anxiety and chronic pain. Also, many people with depression don’t take antidepressants, and men in particular are less likely to come forward for any type of treatment. Some of the men thought to be healthy might have had undiagnosed depression.
Depression in men was only linked to prematurity in certain situations. After taking all other factors into consideration, the results were only statistically significant for new depression in very preterm births, not for repeat depression, or new depression in moderately preterm births. There were only 2,194 very pre-term births out of a total of 366,499, and the findings were only just statistically significant (as seen by the odds ratio of 1.04 to 1.83). This suggests the results may not be completely reliable.
It's also worth bearing in mind that the study cannot show that depression, in men or women, directly causes the increased chances of preterm birth. This type of study can never account for all the possible confounding factors that might have caused the results.
The researchers say their findings should be investigated with a trial of screening expectant fathers and treating them for depression. This would help us to discover whether the results hold true.
However, depression is a debilitating condition for men and women, which affects not just the person who has it, but their close family. It seems feasible that a pregnant woman whose partner is depressed will see an effect on her own health, and possibly that of her baby.
Depression is treatable, with talking therapies as well as antidepressants. Anyone who is worried they may be depressed should get help from their GP.
