In a study published Monday in the journal Pediatrics, the researchers examined live birth rates in Ontario from 1999 to 2009 in 4.5 million girls aged 15 to 19, with and without a major mental health illness.
The study found pregnancy rates among girls with bipolar disorder, schizophrenia or major depression were not only three times higher, but they also have been declining at a far slower pace than those for adolescent females without a mental health diagnosis.
Although birth rates for both groups of teen girls dropped over time, the gap between them appeared to be widening slightly during the 10-year study period. Among girls with a major mental illness, live births decreased by only 14 per cent, compared to a 22 per cent drop among those unaffected by psychiatric issues.
"Although we do know some of the risk factors behind why girls with mental health illness may be at increased risk of becoming pregnant, pregnancy-prevention programs in most developed countries have not traditionally considered mental health issues," said lead author Dr. Simone Vigod, a psychiatrist at Women's College Hospital in Toronto.
Vigod said girls from low-income families and those who live in rural areas have a higher risk of teen pregnancy, while having already had a child increases that risk further — and those factors also hold true for adolescent females with mental health issues.
While the study didn't look specifically at why girls dealing with a psychiatric disorder have higher rates than unaffected girls, it's known that childhood abuse, low self-esteem and substance misuse are all risk factors for having a teenaged pregnancy.
"And very likely, girls with major mental health problems are more likely to have those kinds of social problems and drug and alcohol problems — problems with impulsivity, feeling badly about themselves," she said.
For example, a teen suffering from depression may find it difficult to protect herself from pregnancy and sexually transmitted infections with a boyfriend because of low self-esteem.
"She just may not have the same capacity to advocate for herself because with depression she feels so negatively about herself. She has trouble asserting herself enough to say, 'We need to use a condom' or 'I don't want to do this.'
"Or if a girl with bipolar disorder is manic or has been drinking, say, then you're disinhibited and then you don't protect yourself as much either."
Besides the obvious life-altering social ramifications, including disrupted education and career goals, teen mothers also have an elevated risk of pregnancy complications, including preterm birth, poor fetal growth and postpartum depression.
"Add to this a pre-existing mental illness, and these young women are forced to manage significant additional challenges," said Vigod.
The authors suggest targeted school-based sex-education programs are needed along with greater integration of reproductive care into adolescent mental-health care programs.
"Interventions that target and integrate reproductive and mental-health care for young women are crucial to ensure we are providing the best care possible for adolescent mothers," said co-author Cindy-Lee Dennis, a senior scientist at the Women's College Research Institute.
"Having these programs and offerings in place will also help reduce teenage pregnancy and improve mother and child health outcomes."
Vigod said current public health pregnancy-prevention programs are obviously having an effect overall, as demonstrated by the 22 per cent drop in the rate of births to teenaged moms during the study.
"But with these girls, it seems to be a bit more of an immutable problem," she said of those with serious mental health issues.
"What if there was assertiveness training involved in the sex ed — not just that you need to use a condom to protect yourself from pregnancy and sexually transmitted infections, but more specific training about what you do if you feel badly about yourself?"
The next stage for any followup research would look at how teens with psychiatric disorders fare as mothers and how their illness affects children.
Overall, adolescents are more prone to developing postpartum depression than older moms, Vigod said.
"I think what we're showing in this study is nobody ever thought about prepartum.
"This study highlights that girls with major mental health issues are a population that needs to be paid attention to if we really want to optimize the overall health of mothers and babies, prevent transmission of mental health issues from parent to child and through the generations.
"I would argue that in utero is where that starts."
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