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Is it really harder to get pregnant in your 30s?

Is it really harder to get pregnant in your 30s?

Catherine Poslusny | June 15, 2021 | trying to conceive
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Having a baby, or babies, in your 30s is the new norm. Maybe you waited because you were focusing on other life goals such as traveling, completing an education, or establishing a career. Maybe you just weren’t ready yet. Either way, you’re not alone. These days, American women in their mid-to-late 30s are giving birth at a higher rate than women in their 20s, according to the latest data from the U.S. Centers for Disease Control and Prevention (CDC) (1).

On the other hand, delaying parenthood comes with the looming question — will you have a harder time getting pregnant once you do start trying? Good news! The data on conceiving in your 30s isn’t necessarily as stark as it’s made out to be. Here, we dig into your most pressing questions about age and fertility and what really happens to your chances of getting pregnant after you turn 30.

How does aging affect female fertility?

According to the American College of Obstetricians and Gynecologists (ACOG), women are most fertile in their late teens to late 20s (2). Your fertility starts to gradually decline as you get older — by ‘older’ science means around the age of 32 — then decreases more rapidly after the age of 37 years, according to both ACOG and the American Society for Reproductive Medicine (ASRM) (3). 

As the years pass, normal age-related changes cause a decline in both the quality and quantity of your eggs. A woman is born with roughly 1 million egg-containing follicles, but loses two-thirds of these follicles by the time puberty begins. Out of the 300,000 or so remaining follicles, only around 300 will be ovulated during your childbearing years (4). 

What happens to those hundreds of thousands of lost follicles? Most disintegrate in an ongoing process of degeneration called atresia, which unfortunately can’t be controlled. Atresia occurs regardless of whether you have “normal” menstrual cycles or take birth control or fertility medications. However, you can avoid smoking, which may make your eggs age faster (4).

The remaining follicles are what doctors call your ovarian reserve. As your ovarian reserve gets smaller, the follicles that are left become less responsive to follicle-stimulating hormone (FSH). More FSH is needed for an egg to mature and ovulate than was necessary before. Eventually, the follicles don’t respond well enough to produce consistent ovulation, typically leading to long, irregular cycles that may be a sign of perimenopause (4). 

At the same time, the quality of follicles worsens with age. Older follicles may contain either too many or too few chromosomes (4, 5, 6). This increases the chances that an embryo also will have too many or too few chromosomes and makes miscarriage more likely (5). Aging also increases your risk of disorders that may adversely affect fertility, such as uterine fibroids, endometriosis, and tubal disease (3).

However, it’s worth noting here that age isn’t the only factor that affects your ovarian reserve. Even if your best friend is the same age as you, you’re not necessarily going to have the same amount of healthy eggs left in your ovaries. Or, as ASRM notes, “Women with poor ovarian reserve have a lower chance of becoming pregnant than women with normal ovarian reserve in their same age group (4).” 

Meaning: Your egg reserve is unique to you. So while there is a documented interplay between a decline in ovarian reserve and age, it’s also possible to have a sufficiently healthy ovarian reserve in your late 30s. 

If you seek fertility assistance, one of the first tests a reproductive endocrinologist (a specialized OB/GYN) recommends is an evaluation of your ovarian reserve (5).

Ovarian reserve, fertility, and age

Your doctor can check your ovarian reserve by measuring the levels of anti-Müllerian hormone (AMH) in your blood. Typically, AMH levels get lower as your ovarian reserve gets smaller, and they start decreasing faster once you hit your mid- to late-30s. On average, AMH levels in women between 30 and 35 are only 66% of those found in women in their 20s. For women 45 and older, that number drops to 25% (7).

Chromosomal abnormalities in your ovarian reserve are common, no matter your age, but your chances of ovulating an abnormal egg increase as you get older. When you’re in your 20s, about 25% of your eggs may have chromosomal abnormalities. When you’re between 30 and 35, that number is closer to 40%, and it increases by about 0.5% each month. By the time you reach your early 40s, up to 75% of your eggs may have chromosomal abnormalities (8).

While having eggs with chromosomal abnormalities doesn’t automatically make you infertile, it does mean you’ll have a lower chance of ovulating a viable egg (one without abnormalities) during each menstrual cycle. This can decrease your chances of getting and staying pregnant because many chromosomal abnormalities can either prevent implantation of a fertilized egg or lead to early miscarriage (8).

Your percentage of eggs with chromosomal abnormalities increases throughout your life, but the rate that it increases starts getting higher around the time you turn 35. By 45, most women have ovulated their last viable egg, and are essentially infertile, even if they’re still ovulating and having regular periods (8, 9).

IVF and age

Many women turn to assisted reproductive technology, such as in vitro fertilization (IVF), to help them conceive as they get older. However, IVF success rates are still affected by a woman’s age when her eggs are retrieved for the procedure. According to the Society for Assisted Reproductive Technology, a woman 35 or under using her own eggs has about a 50% chance of success for an IVF cycle. Between 35 and 37, that number decreases to just above 40%, and between 38 and 40, that number is more like 35%. From 41 to 42, the chances of success are only about 25%, and from 43 and beyond, there’s only about a 13% success rate for each IVF cycle (10).

If you choose to use donor eggs in your IVF cycle, the chances of success largely depend on the age of the donor, not your age (11).

What are your chances of getting pregnant after you turn 30?

Before we dive into the data, please keep in mind that fertility study data show statistics that reflect a snapshot in time. These numbers are based on data gathered from a specific set of women in a study group or a data set. Consider the numbers  as guideposts that can help to explain how female fertility may change with age. In reality, your experience — or that of your bestie, sister, or cousin — may differ. 

Here are some study results: 

  • One of the largest recent medical studies, performed by scientists from Boston University and Aarhus University Hospital in Denmark, found that 78% of women aged 35 to 40 will conceive within a year, compared with 84% of women aged 20 to 34 (12).
  • A study published in the medical journal Fertility and Sterility looked at how long it took couples of different ages to get pregnant. They found that only 58.4% of those over age 35 conceived within 6 months of trying (13). 
  • According to ASRM, a healthy, fertile 30-year-old woman has a 20% chance of getting pregnant in any given cycle in which she tries. This means that in a group of 100 30-year-olds trying to get pregnant in a single cycle, 20 would become pregnant, and 80 would need to try again the next month (4). 

Dr. Spencer McClelland wants to dispel the myth of the fertility cliff at 35 years old. “While it is true that there exists a relative decline in fertility over time, the truth is that, in absolute terms, women 35 and over are still very likely to conceive without difficulty, and at about the same rate as women under 35,” said Dr. McClelland. Although strong data on this subject are hard to come by, because studies like this are hard to design and execute for numerous reasons (14). 

While Dr. McClelland has a good point, keep in mind that at age 40, women have been statistically found to only have a 5% chance of getting pregnant each month and a 33% chance of having a miscarriage. Meaning that fewer than 5 out of every 100 women would be expected to become pregnant during a given cycle (4). So while you may be able to equally get pregnant and stay pregnant at 28 as at the age of 38, those chances decline significantly at age 40 to nearly impossible at the age of 44. 

That said, Dr. James Grifo, M.D. Ph.D, program director at NYU Langone Fertility center says, “the average age of my patient is 39, and obstetrically, they do quite well,” he said. “Age is not a reason not to try if you want a baby” (15). 

Getting pregnant in your 30s

Let’s dig a little deeper into what you can do to increase your chances of conceiving.

One interesting study, published in Human Reproduction, investigated pregnancy rates among 782 couples who were using fertility awareness-based methods (FABMs) and had sex at peak fertility. Here’s what they found: Women between the ages of 35 and 39 had a slightly less than 30% chance of getting pregnant on their most fertile days — a nice increase from the 20% predicted by ASRM (16). 

The takeaway? Having sex on your most fertile days may be highly effective in helping you to achieve pregnancy in your 30s (or any age!) (16 ).

(For a primer on how to tell when you’re most fertile, check out our blog post on 3 signs of ovulation.)

Note: Your diet can also affect your fertility, for better or for worse. If you’re interested in how your eating habits may affect your chances of getting pregnant, we got you! Here’s where we talk about which foods are clinically proven to help with fertility.

What about male fertility changes and age?

Your age is not the only factor at play. History is filled with stories of men conceiving well into old age, which can make it seem like men are exempt from the effects of age on fertility. However, age does impact the quality and quantity of sperm. The question is: how much does that age-related change affect a couple’s ability to get pregnant?

 

You may have heard that up to one-third of infertility cases may be due to male factors (17). With age, men’s testes become smaller and softer, producing less healthy sperm (4). According to a massive meta-analysis of 90 studies of 93,839 men, age negatively affected semen volume, movement, and the shape and size of sperm (18). For example, aging caused more sperm to have defects like bent or coiled tails in one study (19).

What all this means is it may take longer to get pregnant with an older male partner. One paper found that men over the age of 45 took 5 times longer to achieve pregnancy with their partners compared to men under the age of 25 — even after adjusting for the frequency of sex, women’s age, and lifestyle factors, such as drinking alcoholic or caffeinated beverages (13). 

We've covered a lot of ground here. By now, it's hopefully clear that, even though your fertility declines as you get older, it’s definitely possible to conceive naturally in your 30s. Your fertility depends on your unique situation, and there’s a lot more to your fertility than your age. Age is just one of many factors that can influence your fertility. As one scientist explains, “when assessing the effects of aging on fertility, it would be better to consider the patient's ovarian reserve rather than merely her chronological age” (5). 

So, before you start wondering if you were wrong to wait until now to start a family, give yourself some credit. You weren't ready to have kids back then, and that's totally ok. 

Now, you are. And cheers to that!

Photo by Kyle Bearden on Unsplash

References +
How Not to Waste Another Month When Trying to Conceive
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