The irony of reproductive biology and parenthood is not lost on Suleena Kansal Kalra, MD, MSCE at Penn Fertility Care.
“Most couples spend so much time trying not to become pregnant,” says Dr. Kalra. “Then when they want to achieve pregnancy, they think it’s just going to happen. There’s this myth out there that it’s easy to become pregnant, and it’s not.”
She explains, “A lot of women don’t realize the impact of reproductive aging on fertility.”
The Impact of Reproductive Aging on Fertility
“There’s a pretty slow decline in a woman’s reproductive potential in her late teens and early twenties, and then the decline steepens,” says Dr. Kalra. “Some women are not aware of that.”
It’s not as drastic as it sounds, she adds: “You don’t fall off a cliff at 35. Picture a line that’s gently sloping downward. Then picture the slope steepening after 35. It’s not an abrupt drop.”
Fertility 101: Why Getting Pregnant Gets Harder
“A female has the greatest number of pre-eggs that she’ll ever have in her entire lifetime when she’s still in her mother’s uterus,” explains Dr. Kalra. “At five month’s gestation—around 20 weeks—there’s seven million. At birth, there’s two million. At puberty, there’s about 500,000.”
But not all of those eggs are bound to be released from your ovaries for a chance at fertilization, she says. “Throughout the course of our reproductive lifetime, the majority of these pre-eggs are lost. We only develop around 300 to 500 to become eggs.”
In contrast, men hit the reproductive lottery and are lucky enough to produce sperm throughout their lifetime.
Dr. Kalra says the challenge as women get older and approach 40 and beyond is two-fold. The first issue is that the quantity of eggs has declined.
The second issue relates to quality. “Those remaining eggs have been sitting there for however many years. There’s an increased chance of chromosomal abnormalities.”
As she explains, “What happens when an egg and sperm meet is that the egg has to divide in half to make room for half of the genetic material from the sperm. As eggs age, they get less adept at cleaving in half and they take over an extra set of chromosomes, increasing the chance of chromosomal abnormalities in the embryo. This also increases the rate of miscarriage.”
Why Getting Help Is Important
Dr. Kalra admires her patients’ bravery. For some women, just coming to the office is a huge step.
“If you’re having difficulties getting pregnant, it takes a lot of courage to say, ‘I need help. I don’t know what’s going on.’"
That’s why the Department of Health and Human Services’ Office on Women’s Health recommends that you see a doctor if you’re over 35 and have been trying to get pregnant for more than six months.
“The important thing to keep in mind is that the majority of people do still get pregnant on their own. Your age is not depressing. It’s just something you have to be aware of,” says Dr. Kalra.