Getting pregnant after 35 may be more difficult than at age 25, but it's not necessarily impossible. You can likely think of at least a few friends who conceived after 35, or even after 40. So what are your real chances for getting pregnant after age 35? Why is it more difficult than in your 20s and early 30s? And why do doctors recommend seeking help getting pregnant sooner than later?
Fertility and Age
If you follow the news, you've no doubt seen the myriad of features focusing on women waiting until after age 35 to have children and having trouble getting pregnant. But not everyone has trouble getting pregnant after age 35. You may know of families who got pregnant quickly in their late 30s, or even early 40s. However, statistically speaking, your chances of getting pregnant after age 35 are lower.
Fertility peaks in most women in the 20s, and gradually begins to decline in the late 20s. At around age 35, fertility starts to decline at a much more rapid pace. For example, some research has found that in any given month your chances of getting pregnant at age 30 are about 20%. At age 40, your chance of getting pregnant in any given month is just 5%.
Don't confuse this, however, with the odds of getting pregnant overall. This is a per month odd, not per year. Also, many studies struggle to determine how much of the lower conception rate is due to lower fertility and how much is due to less frequent sex.
One study of 782 couples looked at the odds of conceiving based on the day of sexual intercourse before ovulation. The women used body basal temperature charting to track ovulation, and for both younger and slightly older women, the most fertile day was two days before ovulation. For women age 19 to 26, sex on their most fertile had a 50% chance of leading to pregnancy. For women age 35 to 39, the odds were 29%.
While we're discussing the effect of female age, it's important to mention that your partner's age matters as well. Male fertility doesn't decline the same way female fertility declines, but male age does matter.
Remember the study I just mentioned above that found women age 35 to 39 had a 29% chance of conceiving on their most fertile day? That same study found that if their partner was five years older, the couple's odds dropped to 15%. Essentially, their odds halved.
Also keep in mind that these are the odds of conception. That doesn't necessarily mean the pregnancy will lead to a live birth. Miscarriage rates are higher for older mothers and fathers, which I discuss more below.
Why Fertility Declines
Women are born with all the eggs they will ever have. While we are born with over a million eggs, by puberty just 300,000 are left. From this huge number of eggs, only 300 will ever become mature and be released in the process known as ovulation.
Way before menopause begins, our bodies' reproductive capabilities slow down, becoming less effective at producing mature, healthy eggs. As you age and come closer to menopause, your ovaries respond less well to the hormones that are responsible for helping the eggs ovulate.
This natural decline of fertility happens in the healthiest of women, though bad health habits, like smoking, have been shown to speed up the decline of fertility.
Increased Risk of Birth Defects and Miscarriage
Besides the ovaries being less likely to produce mature eggs for ovulation, age also increases the chances of genetic problems.
This is the reason for the increased risk of Down Syndrome babies in women over age 35. At age 25, 1 in 1,250 women will give birth to a child with Down Syndrome. At age 30, it's a 1 in 952 risk, and by age 35, the chance is 1 in 378.
The risk for miscarriage also rises with age. About 10% of pregnancies end in miscarriage for women in their early 20s. By the early 30s, 12% of women experience miscarriages. After age 35, 18% of pregnancies will end in miscarriage. And in the early 40s, 34% of pregnancies end in miscarriage.
Fertility Treatment Success Rates After Age 35
According to statistics collected by the Center for Disease Control, the percentage of live births from IVF procedures using the mother's eggs decreases with age. At age 31, the percentage of live births after IVF treatment was about 38%. By age 39, the percentage of live births was lower, around 22%. After age 43, the percentage of live births drops to less than 10%.
One way around this is by using an egg donor. Even though IVF success was less than 10% at age 40 using the mother's own eggs, women who used an egg donor (from a much younger woman) at age 40 had a success rate of about 45%. That's an even better rate than women using their own eggs in their early 30s.
Bottom Line on Fertility After Age 35
Whether we like it or not, fertility in women begins to slowly decline in the late 20s, beginning a more rapid decline around age 35. Besides the decreased chance of getting pregnant, women after age 35 have an increased risk of miscarriage. Fertility treatment success also decreases with age, specifically if the couple uses the woman's eggs (as opposed to donor eggs).
Despite these grim statistics, not everyone will have trouble getting pregnant after 35. However, if you are having trouble, and you're older than 35, you shouldn't try on your own for longer than six months. The sooner you get help, the better your chances of treatment success.
More things you need to know:
- We Can't Get Pregnant. Now What?
- 7 Things Every Woman Needs to Know About Fertility (Including information on freezing your eggs.)
- 7 Things Every Man Needs to Know About Fertility
- Symptoms and Risk Factors of Infertility
- A Complete Guide to Baby Making Sex
- Fertility Facts vs Fertility Myths: What You Need to Know
- 10 Things to Stop Doing to Yourself if You're Fertility Challenged
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Age and Fertility: A Guide to Patients. American Society of Reproductive Medicine. Accessed June 5, 2008. http://asrm.org/uploadedFiles/ASRM_Content/Resources/Patient_Resources/Fact_Sheets_and_Info_Booklets/agefertility.pdf
Dunson DB, Colombo B, Baird DD. "Changes with age in the level and duration of fertility in the menstrual cycle." Hum Reprod. 2002 May;17(5):1399-403.