A Danish study recently published in the medical journal JAMA Psychiatry has suggested that there may be a link between depression and the oral contraceptive pill. Many women may take a study like this at face value and be understandable concerned.
How was this study done?
The study looked at whether women who had used the pill (as evidenced by their pharmaceutical prescription records) were at higher than average risk of subsequently being prescribed antidepressant medication (which would mean they had formally received a diagnosis of major depression from a medical doctor).
Who was in the study?
The study design was what researchers call a cohort study. Actual patients were not recruited to participate in the study. Instead the study looked at Danish prescription records of women aged 15 to 34 from 2000 to 2013, looking for a link, or what is termed an association.
Who was not in the study?
Most young women are healthy and many take no regular medications, but these women would not register in a study based on the review of prescription records.
The authors of the Danish study did not look at the incidence of depression in young women who had accidental or unplanned pregnancies or termination of pregnancy. This is, in my view a major oversight. I would expect depression rates to be very high in young women who have unplanned pregnancy – and much higher than the background rate of depression in young women.
Can this study’s conclusions be disputed?
Unfortunately, studies like this one are by their nature at a high risk of bias – meaning that an association found – like for example antidepressant use with the pill, might show up for another reason (and not actually be caused by using the pill).
For example, women who present to a doctor (for any reason) are more likely to be diagnosed with a condition than women who do not. They are also more likely to be prescribed a medication.
Do other studies in the field agree with this one?
12 other international studies have not supported the same conclusion, suggesting no link between depression and the pill.
The study found younger adolescent women included in the study had a higher risk of depression if they took the pill. Why should this be?
As a gynaecologist, it is unusual to prescribe the pill to young teenagers purely for contraception. If young women are sexually active, I am very likely to recommend using barrier methods of contraception like condoms as the pill alone offers them no protection against sexually transmitted infections like chlamydia and HIV.
In younger women, the pill is often prescribed to manage gynaecological problems like heavy or irregular periods. Sometimes it is used to reduce the pain of suspected endometriosis. Sometimes it is used to manage mood swings and “PMS” or the so-called menstrual dysphoric syndrome. Sometimes it is used to improve acne and associated body image issues. In all these cases, it is plausible that conditions women suffer for which the pill was prescribed may be more likely to be associated with depression. This is an example of how confounding factors may result in bias, whereby an association may be suggested, when in fact, it does not exist.
As a young woman needing contraception, what should I do?
There are many options for reliable contraception these days. If you would like to find out more about your options, my advice is to make an appointment to discuss your situation with a specialist gynaecologist.
Cautioning young women against using hormonal contraception on the basis of this study is wrong and may result in unplanned pregnancies – with far reaching consequences for women, possibly including depression.