It was not easy for the mother to accept the news when her third child was born with Down syndrome, while her first two children were born without any health problems. The question that arises in such cases is not only emotional, but also medical: Why does this difference occur between one pregnancy and another in the same mother?
The answer given by the doctors was not related to coincidence or unexpected error, but rather to a factor known in reproductive medicine, which is the mother’s age at the time of pregnancy.
In this case, the mother was over the age of 37 years, an age that is classified within the category in which the chances of giving birth to children suffering from chromosomal disorders, most notably Down Syndrome, are high, especially when the mother is over 35 years old.
This link between age and fetal health is not just a clinical observation, but is based on a large accumulation of scientific research that has studied the effect of aging on the quality of eggs, and on the nature of the cell divisions that occur during the formation of the fetus.
What happens to eggs with age?
A scientific review published in June 2024 in Aging Research in the journal Elsevier indicates that women’s aging increases the likelihood of errors in the process of chromosome segregation within eggs during meiosis. This division is the biological process through which eggs are produced, and any defect in it may lead to the presence of an abnormal number of chromosomes in the fetus.
Over time, not only does the quantity of eggs available to a woman change, but their quality also suffers. Older eggs are more susceptible to genetic errors, which explains the higher rates of spontaneous miscarriage, delayed pregnancy, or the appearance of genetic disorders in fetuses as the mother ages.
Therefore, scientific reviews confirm that egg quality is the factor that most influences the fetus’s ability to grow properly, and that it is directly related to the woman’s biological age.
In the same context, it has become clear that postponing childbirth, for social or professional reasons, poses new medical challenges. With the increase in the number of women who prefer to become pregnant at later stages of life, higher rates of chromosomal abnormalities began to appear, which prompted researchers to reconsider the concept of the “ideal age for childbearing” from a purely biological angle.
Trisomy: a defect that begins inside the cell
One of the most talked about disorders in this context is what is known as trisomy, which is the presence of an extra copy of one of the chromosomes inside the cell.
This includes trisomy 21, known as Down syndrome, in addition to trisomy 18 and trisomy 13, which are conditions that lead to mental and physical disabilities of varying degrees, and may be accompanied by congenital defects in the heart, nervous system, or other organs.
These results did not come from one study, but from several large-scale studies. A large study was published in 2024 that included more than half a million women, and the participants were divided into different age groups. The results showed that the risk of developing trisomy increases gradually as the mother’s age increases, and becomes more apparent after the age of 35, and continues to rise after the age of forty.
In another study published in the official journal of the Scandinavian Federation of Obstetrics and Gynecology Societies, which included data from more than half a million women between 2008 and 2017, the same result was confirmed, as it was found that women over 35 years are more likely to give birth to children with chromosomal disorders compared to younger age groups.
Deformities and birth defects
The results did not stop there, as Elsevier magazine published a synthesis study in November 2024 that included more than 15,000 women, and showed that the risk of congenital malformations is not limited only to chromosomal disorders, but also includes other congenital defects such as cleft lip or cleft palate, in addition to defects in the circulatory system.
The study also indicated that the relationship between the mother’s age and risks is not only linear in one direction, but that the mother’s very young age may in turn carry some risks, although the greatest risk is concentrated at advanced ages.
These results prompted researchers to emphasize the need to develop prenatal screening protocols that are more customized according to the mother’s age group, especially in light of the increasing global trend towards delaying childbirth.
Some studies also called for the need to conduct more research to understand the precise relationship between maternal age and rare congenital malformations, the mechanisms of which are still not fully understood.
A study published in 2021 in Elsevier indicates that advanced maternal age is associated with a wide range of risks that may appear during pregnancy or at birth.
These risks include early and late miscarriage, chromosomal abnormalities, stillbirth, and delayed intrauterine growth of the fetus, in addition to increasing the chances of premature birth, preeclampsia, and gestational diabetes, as well as high rates of cesarean section. However, the study confirms that the extent of these risks varies from one case to another, and that many women over the age of 35 experience completely normal pregnancies.
Egg freezing
On the other hand, modern medical technologies have emerged aimed at dealing with this challenge, most notably egg freezing. It is a medical procedure in which unfertilized eggs are preserved at very low temperatures for later use when needed. The ideal period for this freezing is between the late twenties and early thirties, when egg quality is at its highest levels.
The first successful pregnancy using a frozen egg was recorded in 1986, and since then the technology has developed significantly. However, medical bodies, such as the American Society for Reproductive Medicine, do not recommend the use of egg freezing as a comprehensive solution to avoid the effects of delayed childbearing in healthy women, due to limited data on long-term outcomes, in addition to the psychological and economic aspects associated with the procedure.
Available data indicate that embryos resulting from frozen eggs do not differ significantly in terms of rates of fertilization, implantation, or clinical pregnancy compared to fresh eggs, and there are no clear indications of an increase in congenital malformations.
However, long-term follow-up of these cases is still incomplete, because the number of children born with this technique and followed into advanced life is still relatively limited.
How do doctors view pregnancy after 35 years?
Doctors specializing in obstetrics and gynecology explain that talking about the risk of pregnancy after 35 should not be taken in an exaggerated or frightening way.
Dr. Amr Hassan, Professor of Obstetrics and Gynecology at the Faculty of Medicine, Cairo University, said in his interview with Al Jazeera Net that pregnancy at this age does not necessarily mean the presence of a health problem in the fetus, but it simply means an increase in the chances of some complications, which requires more careful medical follow-up, early examinations, and regular monitoring during pregnancy.
Regarding the most prominent risks related to late gestational age for fetuses and newborns, Hassan explained that there is an increased risk of miscarriage, some chromosomal disorders responsible for fetal deformities and some birth defects, in addition to an increased risk of preeclampsia and gestational diabetes.
He refers to a concept known as “high-risk reproductive behavior,” a term used to describe situations in which the risk of complications increases due to factors such as pregnancy at a very young or advanced age, very close pregnancies, or a high number of pregnancies. These factors may affect the efficiency of the placenta, the growth of the fetus, and thus the outcomes of pregnancy in general.
In turn, Dr. Dina Muhammad, a neonatologist, told Al Jazeera Net that delaying the age of marriage and the resulting delayed age of pregnancy exposes the risk of abnormalities in the egg during the division process, which leads to the fetus suffering from congenital malformations and genetic mutations that affect the completion of the pregnancy itself or the birth of fetuses that suffer from health problems, starting with an increased risk of premature birth and the risk of needing incubators to care for the newborn, and the birth of a low-weight “premature” child and the subsequent health problems related to growth. Chromosomal imbalances also increase the risk of developing some syndromes, such as Down syndrome.
Dina adds that the mother’s age at the time of pregnancy and childbirth constitutes a fundamental factor in the health of the fetus and mother and affects the possibility of the mother being exposed to health complications such as gestational diabetes and preeclampsia, which result in an increased exposure of the newborn to the risk of developing growth-related diseases and sometimes an increased risk of stillborn babies.
Age is not a final judgement
It can be said that pregnancy after the age of 35 is not classified as an absolutely unsafe pregnancy, but it is classified as a pregnancy that requires higher medical awareness and closer follow-up. Age may increase some risks, but it does not determine fate.
With the development of modern medicine, the ability to monitor these risks and deal with them early has become much greater than ever before, giving many women the opportunity to have a safe pregnancy despite advanced age, provided that they have careful medical follow-up and adherence to periodic examinations.
