The decision to embark on parenthood invites a wide range of emotions: excitement, nervousness, joy and sometimes even fear of the unknown. Aside from the emotional rollercoaster, men and women have different paths to becoming parents. One of the main differences between men and women is what’s socially referred to as “the biological clock.”
Due to anatomy, women are born with a fixed number of eggs in their ovaries, while men continue to produce sperm throughout their lives. Why is this important? Because together, eggs and sperm comprise the fundamentals to creating a baby.
As women age, ovarian reserve — which is defined as the quantity and the quality of the eggs remaining in the ovaries — declines, and when all eggs are depleted, menopause starts and reproductive function ends (in terms of conceiving a child with one’s own genetic material). For American women, the decline of ovarian reserve accelerates at around age 35 to 37, and menopause tends to start around age 51.
[See: The Fertility Preservation Diet: How to Eat if You Want to Get Pregnant.]
Why Does it Matter?
Over the past several decades, women have increasingly delayed childbearing. In my practice at Montefiore Health System’s Institute for Reproductive Medicine and Health, I hear many women tell me this delay is mainly due to social reasons including educational and/or professional goals, financial barriers and lack of a partner. Since both the quantity and quality of the eggs diminishes with advancing age, it becomes more and more difficult for women to conceive later in their reproductive life. However, many women still desire to have children of their own, which has resulted in an increase in the number of women who utilize reproductive technologies.
According to data from the Centers for Disease Control and Prevention, the percentage of women with diminished ovarian reserve who used assisted reproductive technologies increased from 12 percent in 2005 to 32 percent in 2014. Moreover, aging is associated with increased prevalence of other disorders that may affect fertility, such as uterine fibroids, disorders of the fallopian tubes and endometriosis (a condition where the lining of the uterus grows outside the uterus).
Advanced age is not only associated with decreased ability to conceive, but also with increased complications during pregnancy. Women who get pregnant at an advanced reproductive age are at an increased risk for first trimester miscarriages — mainly due to abnormalities in the chromosome numbers that are associated with pregnancy at an advanced age. For example, while the rate of first trimester miscarriage is around 13 percent for women who conceive with in vitro fertilization and are younger than 35, this rate more than quadruples for women older than 44. Therefore, the American College of Obstetrics and Gynecology and the American Society for Reproductive Medicine recommend that women above 35 don’t delay too long and undergo a fertility evaluation after six months of trying to conceive, while women over 40 should be evaluated and treated immediately.
In addition to infertility and miscarriage, with advancing age pregnant women are at an increased risk for high blood pressure and diabetes, while their fetuses are at increased risk for stillbirth, neonatal death, intrauterine growth restriction, prematurity and associated complications following delivery, like increased neonatal intensive care unit admission.
[See: Why Can’t I Get Pregnant?]
What Is a Healthy Age to Conceive?
According to CDC data from 2014, preterm birth rates were lowest for women ages 25 to 29 and highest at both extremes of reproductive age, namely for women under 20 and over 35. For women of “advanced maternal age” (traditionally defined as childbearing over the age of 35), pregnancy is also associated with preterm delivery and increased maternal mortality. Despite the fact that women over 35 contribute to roughly 16 percent of all pregnancies, approximately 27 percent of maternal deaths occur in this age group. In other words, while maternal mortality is around 38 women per 100,000 for women over 35 years old, this rate is less than 13 per 100,000 for women under 35.
Given the above statistics, the healthiest age range to conceive a child is between 25 to 29.
What Can a Woman Do?
While this information may seem scary and gloomy, as medical professionals it’s important that we educate our patients and work to increase awareness of the effect of aging on fertility and pregnancy, as these are essential in improving the reproductive health of women. Here at Montefiore’s Institute for Reproductive Medicine, we routinely counsel our patients regarding safe conception and the complications associated with reproductive aging. It’s important that patients know the facts and can make well-informed decisions for their health. If our patients express an interest in conceiving a child, we encourage them to include childbearing in their short-term plans to optimize outcomes for both mom and baby.
However, we know that sometimes pregnancy in the near future is not an option. If this is the case, women are encouraged to speak with their OB-GYN to learn what options may be available to them. Depending on the age and social status of the patient, egg or embryo freezing might be recommended. For single women who don’t have a partner, elective egg freezing is a viable option to preserve fertility. For women who have a partner but who are not currently planning to conceive, embryo freezing (possibly in addition to egg freezing) is a viable option. In this situation, egg freezing may provide the flexibility to use one’s own eggs in the future with a different partner, as needed.
[See: The Real Sperm Killers.]
Although egg freezing provides a viable option to extend reproductive capacity, it should not be viewed as a guarantee to preserve fertility. The likelihood of having a live birth following egg freezing depends on the age of the woman at the time of freezing and the number of eggs frozen. The probability of having a live birth declines with increasing age and decreasing number of the eggs frozen.
While medical technology has improved and the number of options to conceive at a later age has increased, it’s important to keep in mind that women have a limited reproductive life span. Delaying childbearing for various reasons is a very personal decision. If you think you may want to become pregnant, I strongly recommend you start having this conversation with your OB-GYN as early as possible. The more your doctor knows, the better he or she will be able to help and guide you on the path to become a parent.
Dr. Erkan Buyuk i s the Director of the Fellowship Program in Reproductive Endocrinology and Infertility, the Director of Reproductive Tissue Bank and the Director of Fertility Preservation Program at Montefiore’s Institute for Reproductive Medicine and Health, Montefiore Health System. Dr. Buyuk is also an Associate Professor of Obstetrics and Gynecology at Albert Einstein College of Medicine.
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Reproductive Aging and the Biological Clock originally appeared on usnews.com
