Dr. Allison Giles discusses fertility rates, risks to mother and baby, and other considerations for women trying to conceive over age 40
Over the past century, the average age at which women have their first child has increased for many reasons. This change poses newer questions for a growing number of women: “Should I even try?” “Are my risks different than the risks younger women face?” “Will my baby be disabled?” “Is it advisable?” These questions are understandable, and we hear them often. Let’s break them down one at a time.
Should I even try?
Implicit in this question is the reality that fertility declines with age. The estimated rate of infertility in women aged 15 to 34 years of age is 7-9%. By contrast, for women aged 40-44 years of age, the rate is approximately 30%. This is a significant increase, but it also means that 70% of women in the latter age range are not infertile! In other words, as a woman age 40-44, the odds that you will be able to conceive spontaneously are in your favor.
However, due to the increased risk of infertility in this age range, we typically don’t advise this population of women to try as long before getting an infertility evaluation. For example, for women younger than age 35, we advise 12 months of trying to conceive before initiating assessment for infertility. For women 35-40, we reduce that period to six months. In addition, for women over the age of 40, while there is no strict guideline, we don’t usually recommend waiting a full six months.
Are my risks different than the risks younger women face?
Yes. Older women experience first-trimester miscarriage with greater frequency than younger women. Ectopic pregnancy is a life-threatening condition in which an egg implants in a location other than the uterus, and it is more common with increasing age. After age 35, that risk is as high as 4-8 times that of younger populations. Also with age come higher rates of chronic illnesses such as obesity, high blood pressure, and diabetes. These disorders can exacerbate the already-increased risk involved with pregnancy after age 40.
Beyond age 45, there are even more risks. A recent study that looked at almost 37 million deliveries between 2006 and 2015 showed that women age 45-54 years have the highest rates of preeclampsia, gestational diabetes, postpartum hemorrhage, and hysterectomy—as well as c-section deliveries.
Will my baby be disabled?
An over-40 pregnancy does come with increased chances of disability for the baby in addition to risks for the mother. The prevalence of chromosomal abnormalities (DNA irregularities) in babies increases with the increasing age of the mother. There are several theories as to why this may be, including a decreased number of normal oocytes (immature egg cells which eventually become eggs during ovulation) available, or accumulated stress on the DNA strands within eggs, to name just a couple. At the age of 33, the chance of your baby being diagnosed with trisomy 21 (Down syndrome) during pregnancy is approximately 1/400. At the age of 40, this chance increases to 1/70. By age 45, this chance is about 1/19.
So too does the chance of congenital disabilities increase with age. The U.S. National Birth Defects Prevention Study found that women greater than age 40 are at increased risk of having babies with multiple types of heart defects, genital abnormalities, skull deformities, and esophageal malformations.
Is it advisable?
This is a very personal question. For many women, the first opportunity to have children comes about in her 40’s. For others, this is a time when decisions about expanding the family are made. Achieving a healthy pregnancy and birth over 40 requires a preconception visit with your OB/GYN. Here, you and your doctor can discuss your specific risks based on your own health and family history as well as develop a strategy for obtaining the best outcome. Often, this will include the option of early genetic testing, meeting with a high-risk pregnancy specialist if appropriate, and more frequent visits with your OB/GYN.
While the journey may hold more challenges and difficult decisions, it is possible for women to conceive and maintain pregnancy over the age of 40. Should you choose to try, we’ll be here every step of the way.