Trying to Conceive After 35 – What are the Risks of Birth Defects?



A pregnant woman


Women all over the world have begun postponing motherhood for a wide variety of reasons. For some it has been the need to focus on a career and create financial stability, while for others it can simply be attributed to not meeting the right person. Even though it is perfectly normal for a woman over the age of 35 to take longer to conceive than a younger woman, the number of mothers over the age of 35 continues to rise. In fact, between 1978 and 2000, the National Center for Health Statistics stated that the birth rates for women aged 35 to 44 more than doubled.

One pressing question, which many women over the age of 35 have concerning the potential of becoming a mother at this age, is whether their unborn child will be at risk of a birth defect.

Age and Fertility

According to Web MD, age does play a major role in a woman’s fertility. Fertility is at its highest during a woman’s 20s. From the age of 23 to 31, a woman is at her most fertile. From then fertility declines by 3% each year until a woman turns 35. After 35, fertility begins to deteriorate quickly. By the age of 39, she will be half as fertile as she was at 31 and between 39 and 42 this is halved once again. The American Society for Reproductive Medicine concurs; stating that roughly one-third of all women aged between 35 and 39, as well as two-thirds of women over 40 years, have fertility problems.

Most women over 35 will have a perfectly healthy pregnancy, although they are subject to higher risks than other age groups. Most of these risks can be managed under a doctor’s supervision.

Chromosomal Abnormalities

Women over the age of 35 are more likely to have children who are born with chromosomal abnormalities, such as Down Syndrome. At age 35, the risk of Down Syndrome is roughly 1/350, according to the Southern California Center for Reproductive Medicine. By the age of 40 the risk of a child being born with some sort of genetic abnormality is as high as 1/38. Women over the age of 45 are urged to be more careful with their pregnancies as the risk of having a child with a genetic abnormality skyrockets to 1/12.

During meiosis, when the egg cell eradicates most of its 46 chromosomes so that it can make way for the male’s genetic material, is when age-related chromosomal issues usually arise.  Minute spindles work to separate the chromosomes. As a woman ages, these spindles become detached from the chromosomes, and it is this detachment that causes an abnormal number of chromosomes in the egg, which is otherwise known as aneuploidy.  This commonly occurs in 33 percent of eggs at age 35, and at age 40, this percentage increases to 50 percent.

It is therefore recommended, by the American College of Obstetricians and Gynecologists (ACOG), that pregnant women who are older than 35 years should have prenatal testing to diagnose or rule out any chromosomal abnormalities.  Approximately 95 percent of women who do have prenatal testing done, will find that their babies are perfectly normal. If the prenatal tests show no chromosomal defects, and the mother is otherwise quite healthy, then the likelihood of the baby being born with any birth defects at age 35, is not any worse than if the mother was in her 20s.

Non-chromosomal Birth Defects

After age 35, there is also a presumed increased risk of non-chromosomal birth defects and pregnancy complications. These include pre-eclampsia, gestational diabetes, and intrauterine growth retardation.

Reducing Your Risks

You can reduce pregnancy risks by seeing a doctor before trying to conceive so that your doctor can do a complete physical. This way you will be able to discuss any medical conditions and medications with your doctor.

Begin taking a daily prenatal supplement that contains at least 400 micrograms of folic acid at least three months before you start trying. Continue to take it through the first month of pregnancy to help prevent neural tube defects.

Nutritious foods should be a major part of your diet. Try to include foods that contain folic acid, such as in leafy green vegetables, oranges and orange juice, peanuts, fortified breakfast cereals, and enriched grain products.

Quit smoking or drinking alcohol excessively, before and after conception.

  • Pam Tully

    This article doesn’t mention one of the most important risk factors for birth defects, which is paternal age. Many articles and papers quote statistics for birth defects or risks relating to the age of a mother, but these often do not mention how the age of the father may have more of an influence. Older fathers are more likely to have children and grandchildren with bipolar, schizophrenia, autism, ms and Downs syndrome. Research is now turning it’s attention to fathers and sperm quality and as geneticist John Crow writes;

    DNA in sperm degrades as men age and can then be passed along to children in permanently degraded and irreparable form, which they likely pass on as well, means that the “greatest mutational health hazard to the human genome is fertile older males”. He described mutations that have a direct visible effect on the child’s health and also mutations that can be latent or have minor visible effects on the child’s health; many such mutations allow the child to reproduce, but cause more serious problems for grandchildren, greatgrandchildren and later generations

  • ash32

    This article fails to mention all of the risks associated with advanced paternal age, besides the abnormalities mentioned by Pam Tully, which are alarming.

    Studies in the past ten years show male fertility declines significantly with age and drops rapidly between 40 and 45 .The idea that a man can easily get a woman pregnant at any age is a myth. The older a man gets, the less likely he is to get a woman pregnant, the longer on average it will take, and the more likely the woman is to have a miscarriage, a stillbirth, a premie or a child with Down’s Syndrome.

    A man’s fertility peaks in his 20s and declines steadily each year thereafter. According to the National Institute of Health, the peak year for pregnancy success rates for men in their forties is 41 and success rates decline sharply between 41 and 45. Studies on mice and in fertility clinics concluded that a man’s fertility drops 7% each year between 40 and 45, thus cutting it almost in half, and `10% with each passing year and that’s in addition to the drop by age 40. By 40, pregnancy attempts are 70% more likely to fail compared with a man 30 or younger and 60% of sperm lack mobility. By age 50, 80% of sperm are DOA . A strong swimmer can still get through, it’s just less and less likely with each year after 40.

    In France, where more and more men have been postponing childbirth until their 40s, birth rates have dropped steadily because older men are not as successful as younger men at getting women pregnant.

    In the past when older men could not get there partners pregnant, researchers simply blamed it on the declining fertility of women in their 30s, with whom older men are usually paired. The reality is it’s a combination of both ages and fertility levels.

    Miscarriage rates are 5x higher if the male is 40 and 10x if he is 50. The risk of premies and stillbirths doubles at 45.Risk for a child with Downs Syndrome increase significantly if the male is 40 or over.

    Men 45 and older take, on average 5x longer to get a woman pregnant and are 5x more likely to take a year or more to get a woman pregnant compared to a man in his 20s.

    • Dave Bryant

      Not even accurate, like a lot of misinformed people. Testosterone wreaks havoc on viable spermatasoa. If a man has lazy sperm then he is less likely to impregnate a woman aging with him unless she has had children, but a young woman can very easily become pregnant by a man in his 40s,50s and 60s….If he can shoot it and doesn’t have prostate/libido issues.

Last modified: June 12, 2014