A recent Canadian study has linked mood disorders to premature births. Pregnant women suffering from either bipolar disorder or clinical depression were the subjects of the study, and both conditions were shown to increase the likelihood of early delivery. Researchers from the Women\u2019s College Hospital and the Institute for Clinical Evaluative Sciences in Toronto, Ontario, analyzed the medical records of more than 5,500 women who had been diagnosed with one or the other of these two common forms of mental illness. All of them had given birth to a single child between the years 2003 and 2011, and all had been hospitalized within the last five years for mental health treatment. The control group consisted of more than 432,000 pregnant women with no previous history of depression or bipolar disorder. The study was designed to test for a number of birth results, including: \tPre-term birth (under 37 weeks) \tHigh birth weight (above the 97th percentile) \tLow birth weight (below the 3rd percentile) \tEarly infant death (within 28 days of birth) \tStillbirth \tCongenital malformations \tMedical complications requiring hospitalization shortly after birth Virtually all of these negative outcomes were found in greater frequency among women suffering from depression or bipolar disorder. Interestingly, the two groups were on opposite ends of the spectrum with respect to birth weight: babies born to women with depression were 22 percent more likely to have low birth weights in relation to gestational age, while women with bipolar disorder had a one-third greater chance of giving birth to babies that were larger and heavier than normal. But of all the problems measured, none was more affected by the presence of a mood disorder than the rate of premature birth. Women with major depression or bipolar disorder were twice as likely to have had their babies before their due dates, even after statistical adjustments were made for confounding variables such as the age of the mother, the sex of the infant and any serious physical health problems that preceded pregnancy. Early birth is an alarming outcome because it is a known risk factor for medical complications in newborns. That relationship was confirmed by this study, as kids born prematurely to moms with bipolar disorder or depression suffered from health problems that often required re-hospitalization in the weeks and months following birth. But this frightening pattern was not confined to boys and girls born prematurely. Even when babies born to women with mood disorders reached full term, they were still more likely to experience health complications following birth. This shows the presence of these mental health disorders is disruptive to fetal development in general, bringing an unpredictability to the prenatal process that is stressful for prospective parents and a cause of concern for medical professionals. Approximately 11 percent of non-pregnant women of reproductive age will experience serious depression in any given year. Meanwhile, bipolar disorder is the sixth-leading cause of disability for women in this same age group. Both conditions can be life-altering and life-threatening (suicide is strongly associated with both), and the threat they pose to the unborn and to vulnerable infants is just another unpleasant aspect of their existence. At this stage, the specifics of the relationship between depression, bipolar and disturbing birth results is not well understood. Mental health troubles undoubtedly have physical effects, including the stimulation of stress hormone secretions that can have toxic effects in the body. But exactly how and why this would lead to greater numbers of premature births is uncertain. There is an obvious symbiosis between a mother and her unborn child that can put the latter in harm\u2019s way if the mother\u2019s health is compromised. With respect to mental health problems and their physiological effects on mother and child alike, more research is needed to clarify the depth and breadth of this connection. But awareness that such a risk exists is important, because it gives prospective parents the opportunity to make more careful family planning decisions and to discuss important facts with their physicians once the decision to have a child has been made.