The trend toward older parenthood looks set to continue, with more women in their 30s having babies now than women in their 20s. Are there more risks involved with pregnancy and birth as maternal age rises? We check out the most recent evidence.
Recent preliminary data from the Centers for Disease Control and Prevention (CDC) indicate that in 2016, for the first time in three decades, birth rates among women aged 30 to 34 surpassed those among women aged 25 to 29 in the United States.
The average age that women are having their first child is currently at around 28 years of age, up from
Studies report that people may delay parenthood until 35 or older for a number of reasons.
These reasons include women reaching higher education levels, establishing their career, improved methods of contraception, social and cultural shifts that have left women feeling not ready to have children, lack of childcare, low benefit levels, inflexible workplace policies, economic or housing uncertainty, and unemployment.
Another reason why women are going through pregnancy later in life could be down to improved fertility options, such as IVF.
Pregnant women over the age of 35 and having their first baby have been termed as being advanced maternal age (AMA) or older mothers, or they are being referred to as an elderly primigravida or elderly primipara. The terms “advanced age” and “elderly” have negative connotations for someone of just 35 years. Are these terms unfounded, or does being over 35 pose a serious risk for the mother and baby?
Everyone is aware of the ticking of the biological clock, but does your 35th birthday represent a particularly special milestone in biology? Do you hit 35 and suddenly become “high risk” overnight?
Women are delivering healthy babies throughout their 30s and beyond. The age of 35 is simply an age that certain risks become more worthy of discussion.
While these risks become slightly more likely after hitting 35 years old, this does not mean that they will have a significant impact on everyone in their mid-thirties and older.
Decline in fertility
Women are born with all the eggs they will ever have. As females age, the likelihood that they will get pregnant reduces due to the declining number of remaining eggs and their reduced quality.
Fertility also declines in men with age due to declining sperm counts, motility, and semen volume. These age-related factors combined can make it more difficult for women to become pregnant.
Certain genetic risks present more often in pregnancy as women age. For example, the rate of having a baby with Down syndrome accelerates with maternal age.
While the rate of an embryo having Down syndrome at the 10-week mark of pregnancy is
Researchers from the Albert Einstein College of Medicine of Yeshiva University in New York learned that the genetic process of recombination could be responsible for the increased risk of conditions such as Down syndrome.
Recombination is the process in which pairs of chromosomes exchange genetic material before separating. The team found that in older mothers, the process of recombination may be less regulated, which may lead to abnormal chromosome numbers in sex cells or large chromosomal rearrangements.
The risk of miscarriage climbs gradually with the mother’s age.
Stillbirth is more likely in older women than younger women. A
Furthermore, the stillbirth rate has been
Women aged 35 years and older are often recommended to be induced as they approach their due date because of the increasing risk of stillbirth with gestational age. Around
The reasons that stillbirth rates increase with maternal age are currently unclear.
The researchers identified increases in the risk of gestational diabetes, placenta previa, breech positioning of the baby, emergency cesarean delivery, postpartum hemorrhage, preterm birth, low birth weight, and high birth weight. Other
“We already knew that older women were more likely than younger women to experience health problems during their pregnancy,” said Dr. Adnan I. Qureshi, director of the Zeenat Qureshi Stroke Institute in St. Cloud, MN. “Now, we know that the consequences of that later pregnancy stretch years into the future.”
Dr. Qureshi and colleagues found that all the risks, except for hemorrhagic stroke, were explained by well-known risk factors for cardiovascular disease – such as high blood pressure, diabetes, and high cholesterol – that older pregnant women face.
In a group of mice that represented women over 35 years old, muscle contraction properties in the uterus were found to be impaired, less sensitive to oxytocin, and have reduced mitochondria numbers, all of which suggest that the uterus muscles are less able to contract properly. Furthermore, researchers found changes in progesterone signaling, which triggered a delay in labor.
“Our research highlights that there are key physiological and cellular changes associated with a mother’s age that result in labor dysfunction,” explained Dr. Rachel M. Tribe, lead investigator of the study at King’s College London. “Timing of delivery and progress of labor is directly related to maternal age, and this can cause complications during birth.”
Babies who are born at a low birth weight often have more respiratory, cognitive, and neurological problems, while preterm babies are more likely to have heart defects, brain damage, lung disorders, and delayed development.
Some studies have indicated that there is an elevated risk of low birth weight (under 2.5 kilograms) and preterm birth (before 37 weeks of pregnancy) for women aged 35 or older. However, a recent study – conducted by Mikko Myrskylä, director of the Max Planck Institute for Demographic Research, and Alice Goisis, from the London School of Economics in the U.K. – suggests that a mother’s age is not the reason.
The research, published in the American Journal of Epidemiology, found that the reasons are more likely to be associated with individual circumstances or behaviors that are more common in older adults.
Potential candidates for these factors could be fertility problems, which are connected with poor birth outcomes, maternal stress, and unhealthy behaviors.
“Our findings suggest that women should not be concerned about their age per se when considering to have a child,” said Myrskylä. “It seems that individual life circumstances and behavioral choices are more important than age.”
People deciding whether to postpone parenthood should take into account declining fertility and increases in the risk of miscarriage and birth complications. Stillbirths are relatively rare, but the risk remains higher for older women than their younger counterparts and increases in the final weeks of pregnancy.
There are, of course, many plus points of putting off motherhood until after age 35. Children of older mothers have been found to have fewer behavioral, social, and emotional difficulties.
According to another
“The benefits associated with being born in a later year outweigh the individual risk factors arising from being born to an older mother. We need to develop a different perspective on advanced maternal age. Expectant parents are typically well aware of the risks associated with late pregnancy, but they are less aware of the positive effects.”
Despite the risks, most women aged 35 and older will have a normal pregnancy with few birth complications, and go on to deliver a healthy baby.