Is there a perfect time to have a baby? Explore the various benefits and risks of giving birth sooner — or later.

AGES 20 TO 24

YOUR BODY
These are your most fertile years. Your periods are probably regular, and most, if not all, of them are ovulatory. Even now, however, you may not conceive exactly when you want to. The average woman between 20 and 24 years old has about a 20 percent chance each month of getting pregnant when she has unprotected intercourse.

Once you do conceive, your blood pressure will probably be checked at each prenatal appointment, even though most women in their 20s have only a small risk of hypertension during pregnancy. New research shows that you have about half the risk of gestational diabetes that women in their 40s do, which is why recent guidelines from the American Diabetes Association suggest eliminating the once routine test for gestational diabetes in women age 25 or under.

YOUR EMOTIONAL SELF
How you feel about your pregnancy may depend, in great part, on other things in your life. Some women who postpone job advancement to have a baby feel ambivalent or resentful at first, says Diane Ross Glazer, Ph.D., a psychotherapist in Woodland Hills, CA. "Another concern is body image, which is a bigger issue for most women in their 20s than for those who are older. Also, a woman at this age is likely to be focused more on her marriage than on other parts of her life, such as her job, and adding a third person into the mix may be difficult," says Glazer.

RISKS TO YOUR BABY
The miscarriage rate during these years is about 9.5 percent, the lowest it will ever be. Because your eggs are still relatively young, your baby is much less likely to be born with a birth defect such as Down syndrome (1 in 1,667 births among women age 20) or other chromosomal abnormalities (1 in 526 among women age 20). Yet more infants with these disorders are born to women in their 20s because those in this age group have more babies and women past 35 are more likely to be offered screening tests and may elect to terminate a pregnancy in which the fetus has a birth defect.

AGES 25 TO 29

YOUR BODY
If you exercise and eat sensibly, and continue to do so throughout your pregnancy, you should have an easier delivery and be able to get your body back in shape more quickly than a less fit woman might. Although this is true at any age, in your 20s you are more likely to be at optimal fitness, making delivery and postpartum weight loss easier. In terms of long-term health, if you begin conceiving in your 20s, you may be at decreased risk for breast cancer and ovarian cancer, according to some studies. Doctors think that hormonal changes that occur during ovulation (increased estrogen and progesterone), which stimulate the ovaries and breasts every month, may raise the risk of these cancers; the more often you’re pregnant, the less often you ovulate.

YOUR EMOTIONAL SELF
In your late 20s you’re more likely to be established in your work life and, depending on when you married, your relationship with your husband may also be in better shape to handle the changes that parenthood brings.

RISKS TO YOUR BABY
The miscarriage rate is 10 percent, only slightly higher than for women five years younger. At age 25, your chances of delivering a baby with Down syndrome are 1 in 1,250, and there’s a 1 in 476 chance of having a baby with any chromosomal abnormality.

AGES 30 TO 34

YOUR BODY
Fertility begins to decline at age 30, but this change happens gradually, over the next five years or so. If you need infertility treatment, your chances of success are higher than they are for an older woman. For women under age 35 the success rate of in vitro fertilization (IVF), for example, is 25 to 28 percent; for those over age 40, that rate drops to 6 to 8 percent. One study found that the rate of cesarean sections was close to two times higher among women ages 30 to 34 than among those in their 20s, although doctors don’t know why.

YOUR EMOTIONAL SELF
"Women who have been fully involved in their job in their 20s often feel emotionally ready to start a family as they enter their next decade," says Glazer. "And they have the energy and the resources to do it. But they may also feel pulled in different directions. They worry about whether they’ll be able to return to their work life — or whether they’ll even want to."

RISKS TO YOUR BABY
The miscarriage rate is 11.7 percent. By age 30 your risk of having a baby with Down syndrome is 1 in 952, and a baby with any chromosomal abnormality, 1 in 385.

AGES 35 TO 39

YOUR BODY
Fertility continues to decline after age 35, and it takes a nosedive at age 38, says Benjamin Younger, M.D., executive director of the American Society for Reproductive Medicine, in Birmingham, AL. "The decline is due mostly to the fact that the woman’s eggs are aging, and they become more difficult to fertilize," he adds.

Up until age 35, most doctors suggest that couples have unprotected intercourse for a full year before seeking infertility treatment; that time period is reduced to six months for women over 35. "The greatest problem for infertile couples is delayed treatment, because there’s a big difference in success rates between a woman in her late 30s and one in her early 40s," says Ruth Fretts, M.D., clinical instructor of obstetrics and gynecology at Harvard Medical School. "In fact, many infertility clinics won’t accept patients if they’re older than 39 or 40."

The risk of high blood pressure during pregnancy is about double for women over 35 compared with younger ones; hypertension affects about 10 to 20 percent of pregnant women in this age group. Gestational diabetes is two to three times more common in women over age 35 than in younger women, and recent studies show the risk is even higher if the woman has gained weight over the years.

The chance of having a cesarean section is about twice as high for women ages 35 to 39 as for those in their 20s, possibly because labor tends to take longer in older women. "When the second stage of labor surpasses two hours, obstetricians often intervene and do a C-section to reduce stress on the fetus," says Gertrud Svala Berkowitz, Ph.D., professor of obstetrics and gynecology and reproductive science at the Mount Sinai School of Medicine in New York City.

YOUR EMOTIONAL SELF
This is the age when your doctor might recommend amniocentesis or some other prenatal screening — which for many women is anxiety-provoking while they await results — because the risks of having a baby with Down syndrome or another type of chromosomal disorder begin to rise significantly.

RISKS TO YOUR BABY
The chance of having multiple births, especially twins and even triplets, increases significantly in your late 30s (and early 40s). "This is probably due to the fact that the hormonal stimulation of the ovaries changes slightly as a woman ages, increasing the chances that they’ll release more than one egg," says Dr. Younger. "It could be Mother Nature’s way of compensating for the fact that more eggs are likely to be defective." Women who take fertility drugs are also at higher risk of multiple births because the drugs stimulate the ovaries to produce more eggs. Even so, the chance of twin, triplet, or other multiple births is still relatively slim.

The miscarriage rate rises after age 35 to close to 18 percent. Rates of stillbirths are about twice as high among older pregnant women than younger ones, according to recent studies, although the reasons are unknown.

AGES 40 TO 44

YOUR BODY
First the good news: A recent study shows that women over 40 who have babies without help from fertility drugs or other assisted reproductive technologies tend to live longer than those who don’t. Why? One theory is that estrogen, which is still produced in abundance in fertile women, has life-lengthening effects on the heart, bones, and other organs. However, fewer than 1 percent of women ages 40 to 44 have babies. The chance of becoming pregnant during any one month drops to only 5 percent after age 40.

How well you carry and deliver a baby in your 40s depends on several factors, including your level of fitness, overall health habits, and whether this is your first baby. "The biggest complaint I hear among my pregnant patients in their 40s is how tired they feel," says Jennifer Niebyl, M.D., a professor and head of the department of obstetrics and gynecology at the University of Iowa. "Hormonal changes in pregnancy make all women feel tired, but fatigue seems to be more pronounced in older ones and can be compounded if there are young children to care for."

If you’ve already had a baby, you may also be more prone to hemorrhoids, pressure on the bladder, prolapsed tissues in the uterus and vagina, and sagging breasts than you would have been 20 years earlier, simply because the muscles and other tissues in these areas have already been stretched. You can minimize these effects by making sure not to gain an excessive amount of weight during pregnancy, keeping moderately active, and doing Kegel exercises to keep your vaginal muscles strong.

YOUR EMOTIONAL SELF
By the time you’ve reached your 40s, you have a wealth of experience and maturity to draw upon when raising a child. Chances are, you’ll also be more patient than you would have been in your 20s. But you’ll probably have concerns. "What I hear most often is, ’I’ll be so old by the time this baby starts college!’" says Glazer. "Or a couple will look down the road and see that their nest won’t be empty until they’re 60 or 70. Older parents have to balance feelings of loss of freedom and spontaneity with the joy they’ll feel in raising the child."

RISKS TO YOUR BABY
About one-third of all pregnancies in women ages 40 to 44 end in miscarriage. There are several reasons: The eggs may be defective to start with, the uterine lining may not be thick enough, or the blood supply to the uterus may not be rich enough to sustain a pregnancy. The risks of placenta previa (in which the placenta lies low in the uterus, partly or completely blocking the cervical opening and creating a high risk of hemorrhage) and placental abruption (in which all or part of the placenta separates from the uterine wall) are also increased. Babies born to women in their 40s are also more likely to have lower birth weights (under 5 1/2 pounds).

Risks of chromosomal birth defects rise steadily with each year into your 40s. If you give birth at age 40, your baby has a 1 in 106 chance of being born with Down syndrome and a 1 in 66 chance of being born with any chromosomal abnormality. But by age 44, those risks rise to 1 in 38 and 1 in 26, respectively.

AGES 45 TO 49

YOUR BODY
The percentage of women who have babies in this age group is .03, and the chance of successful infertility treatment drops tremendously. Just being able to conceive and sustain a pregnancy is an achievement and to some degree a reflection of your own good health. "We all hear success stories of women who had children in their late forties through in vitro fertilization," says Dr. Younger. "But more than half of all pregnancies conceived through IVF in women over age forty are produced through donor eggs."

Once you’ve conceived, you’re more likely to undergo rigorous testing than you would if you were younger. Most pregnant women in their 40s have some stress testing to check their cardiovascular health, and they’ll be more closely monitored for signs of diabetes or kidney problems than those in their 20s, says Dr. Younger.

Even if you’re in top physical shape, carrying and delivering a baby will be more difficult than it would be if you were in the same physical shape in your 20s. "Pregnancy, in a sense, is like an athletic event," says Dr. Niebyl. "Blood volume nearly doubles, increasing the strain on your heart, and the extra weight puts some strain on your muscles and joints."

YOUR EMOTIONAL SELF
Most women in their mid-40s are concerned about the health of their baby as well as their own health — with good reason, since there are increased risks for both at this age. But most pregnancies, even among women in their 40s, have good outcomes. The better you care for yourself, the more successful your pregnancy is likely to be.

RISKS TO YOUR BABY
More than half of all pregnancies in women over age 45 end in miscarriage (before 20 weeks gestation). Risk of stillbirth is doubled for women in their 40s, compared with those in their 20s; for this reason, many doctors perform more stress tests and ultrasounds in the last weeks of pregnancy in older women. The chance of chromosomal abnormalities increases sharply. At age 45, there’s a 1 in 30 chance of delivering an infant with Down syndrome and a 1 in 21 chance of having a baby with any chromosomal abnormality. In a 49-year-old those risks rise to 1 in 11 and 1 in 8, respectively.

OVER 50 The average age for menopause is 51, but typically the range runs from 45 to 55. Almost all pregnancies beyond age 50 require some assistance, whether from fertility drugs, hormone supplements, or, more often, donor eggs. Women still ovulating usually have to take progesterone for at least the first two months to maintain the pregnancy. Women who have stopped ovulating need donor eggs to conceive and must take estrogen and progesterone for much of the pregnancy, until the placenta begins to produce those hormones on its own.

At this age, there’s a high rate of complications — including hypertension, kidney problems, and placental problems — that requires strict monitoring and care.

Then there’s the issue of the woman’s age once the baby is born. We all know 50-year-olds who are more energetic and alert than their 20-year-old counterparts, and they have the added benefit of maturity and experience. But women over 50 may need extra energy — not to mention stamina — to awaken every two hours with a newborn or to chase after a toddler.

Statistics show that once a woman has gotten pregnant, if she takes good care of herself and if prenatal screening tests are negative, she’s much more likely to deliver a healthy baby than not — regardless of her age. The rate of fetal deaths has dropped by about 70 percent since the 1960s. That’s great news for all pregnant women.

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