The typical age for having children ranges from about age 20 to age 35. Many women who are older and younger have children, though. Does their age matter to their pregnancy?
A recent study found that the oldest and youngest women giving birth tended to have a higher rate of pregnancy complications.
Mothers aged 17 and younger had higher rates of preemies. Mothers 40 and older had higher C-section rates and rates of babies going to NICU.
However, the younger and older mothers were also more likely to have underlying conditions that may have affected their pregnancy complication risks.
The study, led by D.A. Vaughan, of the Coombe Women and Infants University Hospital in Dublin, Ireland, looked at pregnancy outcomes for women based on their ages.
Specifically, the researchers were interested in outcomes for women aged 17 or younger and women aged 40 or older.
A total of 36,916 women who gave birth to their first child between 2000 and 2011 were included in the study.
The researchers divided the women into five groups based on age: those aged 17 and younger, those aged 18-19, those aged 20-34, those aged 35-39 and those aged 40 and older.
The 17 and younger group included 3.3 percent of the total study group, and 1.7 percent of the study group was aged 40 or older. The majority of the women, 78 percent, were aged 20 to 34.
Then the researchers looked at the rates of preterm (early) birth, birth defects and cesarean sections among the women, as well as how many of their babies were admitted to the neonatal intensive care unit (NICU).
They found that the youngest mothers, aged 17 and younger, had almost twice the risk of delivering a baby early than women aged 20 to 34.
About 9.8 percent of the mothers aged 17 and younger had preterm births, compared to 5.9 percent of the women aged 20 to 34.
However, these younger women were also more likely to be underweight and to smoke during pregnancy, both of which are risk factors for preterm birth.
Meanwhile, babies born to mothers aged 40 and older were 35 percent more likely to be admitted to the NICU and a little less than twice as likely to have a birth defect.
About 23.5 percent of the babies born to women aged 40 and older were admitted to the NICU, compared to 16.8 percent of the babies born to women aged 20 to 34 (and to mothers aged 17 and younger).
The rate of babies admitted to the NICU was 20.2 percent for mothers aged 34 to 39 and 15.8 percent for mothers aged 18 and 19.
Among mothers aged 40 and older, 7.3 percent of their babies were born with a birth defect, compared to 4.4 percent of the babies born to mothers aged 20 to 34.
The older mothers were more likely to be obese and/or to have underlying medical conditions such as high blood pressure or diabetes.
Those conditions can contribute to pregnancy complication risks, and obesity is a risk factor for having a C-section.
About a quarter of the women overall (23.9 percent) had C-sections, but the rate varied considerably by ages.
Among mothers aged 17 and younger, only 10.7 percent had C-sections while 54.4 percent of mothers aged 40 and older had C-sections.
The rate of a trisomy disorder (caused by an extra chromosome) was 1.6 percent among women aged 40 and older. It was 0.3 percent for women aged 20 to 34, 0.9 percent for women aged 35 to 39 and 0.2 percent for mothers aged 19 and younger.
The three types of trisomy disorders are Down syndrome, Edward syndrome and Patau syndrome. The survival rate is low for Edward and Patau syndromes.
The researchers concluded that women who were much younger or older than the average childbearing age are at higher risk for pregnancy complications.
According to Ronald de la Peña, MD, an OB/GYN at Los Robles Hospital in Thousand Oaks, California, and a dailyRx expert, this study helps emphasize the increased risk of pregnancy complications for women at the extreme ages of giving birth.
However, he noted “the discussion is very focused on outcomes and not so much process.”
For example, he said, the authors do not explain why the women getting C sections needed them: whether it was not dilating, not being able to push the baby out, heart rate abnormalities of the baby or another reason.
They also did not report whether the women used a medicine to induce labor, such as pitocin, and whether the women used epidurals or other pain relievers for labor and delivery.
“This study agreed with other studies that identified a higher rate of additional medical problems in the older group, such as obesity, high blood pressure, and diabetes,” Dr. de la Peña said.
However, he said the authors did not report on whether the women had other conditions that could influence the risk for a C section, such as uterine fibroids or an abnormal uterus.
“There is no discussion on the management of labor, and if a standardized method of practice was used,” Dr. de la Peña said. “The twelve year study certain had many patients, but medical practices may change over time and this is not addressed.”
He also noted that the differences in the way obstetrics is practiced in the US versus Ireland may make a difference in how these findings should be viewed.
“It would be instructive to find out what outcomes may result in a similar hospital in the US” using similar criteria, Dr. de la Peña said.
The study was published June 11 in BJOG: An International Journal of Obstetrics and Gynaecology. The research was funded internally, and the authors declared no conflicts of interest.
Copyright © Ronald E. De La Pena, MD. All rights reserved.