How Late Can Women (and Men) Wait to Have a Baby?

After having 13 children and seven grandchildren, German grandmother Annegret Raunigk gave birth to quadruplets — at the age of 65.

After three rounds of in vitro fertilization (IVF), an Indian woman named  Rajo Devi Lohan became a first-time mother — at the age of 70.

And at the age of 96, Ramajit Raghav fathered a healthy baby boy with his 52-year-old wife Shakuntala Devi, their second child in two years.

Modern technology has greatly extended the age at which people can become parents. But how soon do you need to get started if you aren't planning on taking advantage of heroic medical measures?

Women Who Want to Have Children Need to Get Started Early

Hearing about older women's having children, many career-oriented women think that they can wait until 40, 45, or even later to start trying to conceive a baby of their own. The reality is, many women who conceive after the age of 45 are only able to do so with the help of in vitro fertilization (IVF). The longer a woman waits, the harder it is for her to have a child.

Part of the problem is that women have only a limited number of eggs. All of the eggs a woman will ever have are present at birth (actually, before she is born). The two ovaries may start with as many as 6,000,000 immature eggs, each in a tiny follicle. At puberty, one follicle, sometimes two or more, matures to release a viable egg at ovulation, approximately in the mid-point of her menstrual cycle. Throughout her lifetime, a woman will produce, on average, 450 viable eggs, most of which, of course, are not fertilized.

A Woman's Eggs Lose Viability at an Accelerating Rate After Age 30

Throughout a woman's life, however, a process called atresia reduces the number of follicles. By the time she has her first period, already the overwhelming majority of follicles have atrophied, leaving just 300,000 immature eggs. That seems like an unfathomably large number of potential offspring, but atresia continues throughout a woman's reproductive life. The process begins to accelerate about age 32. By age 37, a woman's ovaries house just 25,000 of the immature eggs known as oocytes. By age 51, the number is about 1,000. Normal aging processes, and damage to the ovaries from smoking, pelvic infection, uterine fibroids, chemotherapy, radiation therapy, and other medical interventions result in the release of fewer and fewer viable eggs even if she had not passed menopause.

READ Trying to Conceive? Best Tips for Getting Pregnant

• Even at age 35 or younger, only about 41 percent of eggs can be fertilized.
• By age 37, only about 31 percent of eggs are still viable.
• By age 44, the viability figure falls to 5 percent.
• By age 50, fewer than 1 percent of the eggs released during ovulation are still capable of being fertilized.

Because women start with so many oocytes, pregnancy can and does happen when women are in their forties. But it's really rare without medical assistance by the time a woman turns 50. Even when women aren't using contraception, they have about a one in five chance of getting pregnant in any given month at age 30. The chances drop to one in twenty in any given month by age 40, and almost zero at 50.

How Late Can Men Become Fathers?

Although a woman's supply of eggs is fixed before birth, a man's supply of sperm is in theory limitless. The testes can produce sperm about every 16 days essentially as long as a man is alive, and because a single ejaculation can release as many as 1.8 billion individual sperm, only one of which is need to fertilize one egg, male fertility is not usually as problematic for older couples seeking to conceive as female fertility. That doesn't mean, however, that older men don't have problems becoming fathers.

• Nearly all men over the age of 45 have some degree of erectile dysfunction. It's possible for a man to ejaculate even without an erection, although many men won't try. 
• Obese men at any age tend to have trouble with both ejaculation and sperm production. Fat cells preserve and manufacture estrogen, even in men, reducing activity of the testes.
• Prostate problems impede male fertility. The prostate makes semen. Without the prostate, there is no ejaculate, although the testes may continue to make sperm.
• DNA damage can occur in both eggs and sperm in both men and women, but the problem accelerates with age in men. At the age of 30, both a mother and a father typically pass on about 20 genetic mutations to their children, most of which are harmless. By the age of 40, the mother still passes on 20 mutations to her child, but the father passes on about 40 mutations. By the time a man is 60, the number of mutations is about 60. Older fathers are more likely to have children who have cleft palate, autism, and schizophrenia, and their children are more likely to be born prematurely or have a low birth weight.

For the health of the child, it's better start trying to conceive about as soon as financial and social stability can be established. But how would you know if you need medical help to have a child?

READ A Complete Guide to In Vitro Fertilization (IVF Treatment)

• The overwhelming majority of a man's sperm will be defective. Even if you get test results of a semen analysis reporting "95 percent defect," or even more, this doesn't mean that sperm quality will interfere with your efforts to have a baby.
• Women typically have blood testing for a substance called anti-Mullerian hormone (AMH) to find out if their ovaries are still releasing eggs. It's important to understand that AMH levels can fluctuate, and that while the "normal" range is 13 to 60, higher isn't necessarily better. High levels of AMH are associated with polycystic ovarian syndrome, which interferes with a woman's ability to conceive. Don't panic if your AMH level is on the low end of the normal range.
• Women are often given invasive ultrasound to make an image of the ovaries around the time of ovulation. While it can be thrilling to see your own egg follicles and know that you are still fertile, this test really isn't designed to measure your fertility. It's designed to measure whether you have eggs that could be extracted for IVF. 

Fertility tests help to pinpoint problems in getting pregnant, but they don't guarantee that you will be able to get pregnant if you wait. It's always best for the health of the parents and the health of the baby if conception occurs as soon as the family is ready to provide for the child.