As soon as it was announced that Janet Jackson is pregnant just two weeks shy of her 50th birthday, I was flooded with questions about how women well past age 40 can conceive.
Although it's common knowledge that age negatively affects female fertility, many women still don’t understand just when it is too late to get pregnant. And while advances in assisted reproductive technology have changed the landscape of reproduction for older women, it has also led to confusion about when having a baby is no longer possible and exactly what limitations in vitro fertilization, or IVF, can overcome.
I'm an OB/GYN, fertility specialist, and associate professor of reproductive endocrinology and infertility at USC School of Medicine. Here are the most common questions I get about being over 40 and trying to conceive—and what I tell my patients:
1. How does age affect the process of trying to get pregnant?
A woman is born with all the eggs she is ever going to have. As she gets older, the quantity and quality of her eggs decrease. Once the number of eggs is nearly depleted, a woman enters menopause. However, there is a period of several years before menopause when a woman has eggs and is still ovulating but can no longer get pregnant.
Why is that? The answer is simple: The quality of her eggs is poor. Eggs are cells just like any other cell in the body, and they, too, age as a woman gets older. This means that although eggs may be released during ovulation, there are oftentimes defects in these eggs that do not allow them to be fertilized in such a way as to produce a normal pregnancy.
I like to think of eggs as cars. The first year you have a car it works great. But if you leave that car in your driveway for 15 years, even though you don’t drive it, when you try to start it up again something is likely to have broken down, rusted, or simply quit working.
Eggs go through the same aging process with time and they go through the most important stages of their development when they are ovulated and being fertilized by sperm. So for a woman who is 35, her egg is also 35 when it goes through those critical developmental stages. A woman who is 45 has 45-year-old eggs, and thus they are more likely to have a mechanical “breakdown” during ovulation and fertilization that can lead to either errors in the chromosomes or errors leading to failed implantation of the embryo into the uterine lining.
Simply put, it is more difficult for women over the age of 40 to get pregnant because it's less likely that the egg will develop normally and lead to a healthy pregnancy.
2. Exactly when does the aging process begin?
A woman’s fertility starts to decline after 30, with more significant changes after the age of 35. However, the most dramatic decline occurs after the age of 37 and continues until the age of 45, when the likelihood of pregnancy is exceedingly rare.
This is understandably a hard concept for women to grasp. They don’t feel old when they are 40, so it seems hard to believe that their eggs are so “old” that pregnancy is unlikely and the chance for conceiving may be only 1 in 5. After the age of 40, not only does the chance for pregnancy decline steeply each year, but the chance for miscarriage also rises significantly each year.
Even with the use of IVF, by the time a woman is 45, her chance of conceiving with one embryo that developed from her own egg is 1 to 2 percent, and her chance for miscarriage exceeds 50 percent.
3. Why can’t IVF overcome age?
IVF is not a total cure for infertility. IVF can help women ovulate more eggs in one cycle to optimize fertility. However, IVF cannot reverse the aging process of the eggs that I discussed earlier. We can’t make a 45-year-old egg act like a 30-year-old egg. A 45-year-old egg is a 45-year-old egg, no matter if the woman is trying to get pregnant on her own or through IVF. This is a serious problem for women who strongly desire to have a baby with a genetic link to them.
One of the biggest constraints with IVF in women over 40 is that the number of eggs that grow in response to the stimulation medications used during IVF will decrease as a woman ages because the number of eggs that are available decrease with age. For a woman over age 40, she really needs lots of eggs to compensate for their poor quality due to age, but she simply doesn’t have a lot of eggs. No matter what we do, we can only get a few eggs to grow with each IVF cycle because the ovary does not respond to the medications we use for IVF like it would if she were much younger. The benefit of the ovarian stimulation portion of IVF is less than ideal.
4. OK, so my own eggs aren’t working; what about my uterus?
The amazing thing about the female body is that although egg quality and quantity decline with age, the ability of the uterus to carry a pregnancy typically does not. A woman can carry a pregnancy well into her late 40s without any issues.
Over the age of 40, there is a rise in complications during pregnancy, however, with an increase in high blood pressure, diabetes, and risk of preterm delivery and cesarean section. Many fertility clinics have cutoffs for IVF at age 50 or 53, at which point they require patients to use a surrogate to carry the pregnancy.
5. My eggs aren’t working, but my uterus is. What are my options?
In this situation, a woman can conceive and carry a pregnancy in one of two ways: She can use eggs from an egg donor and attempt to carry the pregnancy herself or through a surrogate. Or, if she froze her eggs when she was younger, she can use those eggs when she is older.
Pregnancy rates are dependent on the age of the egg—so if the egg is young the pregnancy rates are good no matter the age of the uterus. This is why women who are menopausal can get pregnant with a donor egg or with their own eggs preserved at a younger age. They aren’t using their own eggs at the age of 50—they are using their own eggs from when they were younger or they are using someone else’s eggs who is in her 20s.
The bottom line for the 40-plus woman:
If you are 40 or older and want to get pregnant, it's best to have a fertility evaluation right away to assess your chances for conception. Unlike women who are 30 who can try to conceive for a year without needing a fertility assessment, women over 40 have a ticking clock.
The information learned in a fertility assessment can help with family planning by determining how long to try on your own or identify if you should immediately proceed with fertility treatment.