Teen pregnancy tied to increased premature mortality risk in early adulthood

Key takeaways:

• Premature mortality risk was higher with one or multiple teen pregnancies vs. no teen pregnancy.
• Pregnancy before age 16 years was tied to the highest premature mortality incidence vs. pregnancy at older ages.

Teen pregnancy may be an indicator for future premature mortality risk in early adulthood up to age 25 years, according to cohort study results published in JAMA Network Open.

“Although direct deaths during teen pregnancy and childbirth are rare — predominantly from hemorrhage, hypertensive disorders or sepsis — teen pregnancy may be a marker of adverse life experiences preceding and/or during the formative teen years,” Joel G. Ray, MD, MSc, professor in the department of medicine and the department of obstetrics and gynecology at St. Michael’s Hospital at the University of Toronto, the Institute for Clinical Evaluative Sciences and Child Health Evaluative Sciences at the SickKids Research Institute, Toronto, and colleagues wrote. “For example, there is a dose-response association of exposure to adverse childhood experiences — such as sexual and emotional abuse, parental divorce or separation or income decline — with subsequent teen pregnancy, substance use and suicide. Adverse childhood experiences are also associated with premature mortality.”

Ray and colleagues conducted a population-based cohort study utilizing data from 2,242,929 females from April 1991 to March 2021 living in Ontario, Canada. Researchers evaluated the number of teen pregnancies from age 12 to 19 years in the cohort and analyzed how the pregnancy concluded and age at first pregnancy.

Primary outcome was all-cause mortality beginning at age 12 years.

Overall, 7.3% of teenagers had a pregnancy (median age at pregnancy, 18 years), of whom 74.3% had one teen pregnancy and 25.6% had two or more teen pregnancies. Of these pregnancies, 36.8% ended in a birth, 65.1% ended in induced abortion and 11% ended in miscarriage or ectopic pregnancy.

At the end of follow-up, the median age of those with a teen pregnancy was 31 years and the median age of those without a teen pregnancy was 25 years.

Premature mortality risk increased with the number of teen pregnancies: 4.1 deaths per 10,000 person-years for one teen pregnancy (adjusted HR = 1.51; 95% CI, 1.39-1.63) and 6.1 deaths per 10,000 person-years for two or more teen pregnancies (aHR = 2.14; 95% CI, 1.92-2.39) compared with 1.9 deaths per 10,000 persons-years for no teen pregnancy.

Teenagers with a pregnancy had a significantly higher risk for premature mortality from noninjury (aHR = 1.25; 95% CI, 1.12-1.4), from unintentional injury (aHR = 2.06; 95% CI, 1.75-2.43) and from intentional injury (aHR = 2.02; 95% CI, 1.54-2.65) compared with those without a teen pregnancy. For those with a teen pregnancy, noninjury-related premature mortality was 2 per 10,000 person-years, unintentional-injury related premature mortality was 1 per 10,000 person-years, and intentional deaths from injury were 0.4 per 10,000 person-years.

Compared with pregnancy at older ages, pregnancy before age 16 years was associated with the highest premature mortality incidence rate of 5.5 per 10,000 person-years (aHR = 2; 95% CI, 1.68-2.39).

“It remains to be determined whether there is additive value in including teenage pregnancy in the prevention of premature mortality among young and middle-aged women,” the researchers wrote.