Teen pregnancy is associated with a higher risk for premature mortality, both among those who carry the pregnancies to term and those who miscarry, according to a new study.
Among 2.2 million female teenagers in Ontario, Canada, the risk for premature death by age 31 years was 1.5 times higher among those who had one teen pregnancy and 2.1 times higher among those with two or more teen pregnancies.
“No person should die during childhood or early adulthood. Such deaths, unexpected and tragic, are often from preventable causes, including intentional injury,” lead author Joel Ray, MD, an obstetric medicine specialist and epidemiologist at St. Michael’s Hospital in Toronto, told this news organization.
“Women who experience teen pregnancy appear more vulnerable, often having experienced a history of adverse experiences in childhood, including abuse and economic challenges,” he said.
The study was published online in JAMA Network Open.
Analyzing Pregnancy Associations
The investigators conducted a population-based cohort study of all girls who were alive at age 12 years from April 1991 to March 2021 in Ontario. They evaluated the risk for all-cause mortality from age 12 years onward in association with the number of teen pregnancies between ages 12 and 19 years and the age at first pregnancy. The investigators adjusted the hazard ratios for year of birth, comorbidities at ages 9-11 years, area-level education, income level, and rural status.
Among more than 2.2 million teens, 163,124 (7.3%) had a pregnancy at a median age of 18 years, including 121,276 (74.3%) who had one pregnancy and 41,848 (25.6%) who had two or more. These teens were more likely to live in the lowest neighborhood income quintile and in an area with a lower rate of high school completion. They also had a higher prevalence of self-harm history between ages 12 and 19 years but not a higher prevalence of physical or mental comorbidities.
Among all teens who had a pregnancy, 60,037 (36.8%) ended in a birth, including 59,485 (99.1%) live births. A further 106,135 (65.1%) ended in induced abortion, and 17,945 (11%) ended in miscarriage or ectopic pregnancy.
Overall, there were 6030 premature deaths among those without a teen pregnancy, or 1.9 per 10,000 person-years. There were 701 deaths among those with one teen pregnancy (4.1 per 10,000 person-years) and 345 deaths among those with two or more teen pregnancies (6.1 per 10,000 person-years).
The adjusted hazard ratios (AHRs) for mortality were 1.51 for those with one pregnancy and 2.14 for those with two or more pregnancies. Compared with no teen pregnancy, the AHRs for premature death were 1.41 if the first teen pregnancy ended in an induced abortion and 2.10 if it ended in a miscarriage or birth.
Comparing those with a teen pregnancy and those without, the AHRs for premature death were 1.25 from noninjury, 2.06 from unintentional injury, and 2.02 from intentional injury. Among patients with teen pregnancy, noninjury-related premature mortality was more common, at 2.0 per 10,000 person-years, than unintentional and intentional injuries, at 1.0 per 10,000 person-years and 0.4 per 10,000 person-years, respectively.
A teen pregnancy before age 16 years entailed the highest associated risk for premature death, with an AHR of 2.00.