Trying to get pregnant

• There are many steps you can take to help you get pregnant.
• Most couples who try to get pregnant do so within 1 year.
• Talk to your provider about any questions you may have.

Many women now start a family when they are in their mid-30s or older. Today, 1 in 5 women in the United States has her first child after age 35 (1). The good news is that most have healthy pregnancies and healthy babies. However, studies show that women in their mid-to-late 30s and 40s may face some special pregnancy risks. Women should be aware of these risks so they can make informed decisions about their pregnancies, including when to become pregnant.

Does age affect fertility?
Women usually have some decrease in fertility starting in their early 30s. It often takes a woman in her mid-30s or older longer to conceive than a younger woman. Men also may have some decrease in fertility starting in their late 30s (2).

Women over age 35 may be less fertile than younger women because they tend to ovulate (release an egg from the ovaries) less frequently. Certain health conditions that are more common in this age group also may interfere with conception. These include (3):

• Endometriosis (a condition in which tissue attaches to the ovaries or fallopian tubes)
• Blocked fallopian tubes (sometimes resulting from past infections)
• Fibroids (non-cancerous growths in the uterus)

A woman over age 35 should consult her health care provider if she has not conceived after 6 months of trying. Studies suggest that about one-third of women between 35 and 39 and about half of those over age 40 have fertility problems (4). Many fertility problems can be treated successfully.

While women over age 35 may have more difficulty conceiving, they also have a greater chance of having twins (5). The chances of having twins increases naturally with age. Women over 35 also are more likely to undergo fertility treatment, which also increases the chance of twins (as well as triplets and other multiples).

Are women over age 35 at increased risk of having a baby with a birth defect?
A woman's risk of having a baby with certain birth defects involving chromosomes (the structures in cells that contain genes) increases with age. Down syndrome is the most common chromosomal birth defect. Affected children have varying degrees of intellectual disabilities and physical birth defects. A woman's risk of having a baby with Down syndrome is (1):

• At age 25, 1 in 1,250
• At age 30, 1 in 1,000
• At age 35, 1 in 400
• At age 40, 1 in 100
• At 45, 1 in 30
• At 49, a 1 in 10

The American College of Obstetricians and Gynecologists (ACOG) recommends that all pregnant women, regardless of age, be offered a screening test for Down syndrome and certain other chromosomal birth defects (6). Screening tests are blood tests done in the first or second trimester, sometimes with a special ultrasound.  They help evaluate a woman's risk for having a baby with certain birth defects, but they cannot diagnose a birth defect.

ACOG also recommends that all pregnant women have the option of choosing a diagnostic test, such as amniocentesis or chorionic villus sampling (CVS), instead of a screening test (6). A diagnostic test can tell if a person does or does not have a certain condition. Amniocentesis and CVS are highly accurate in diagnosing or ruling out a birth defect, but these tests may pose a very small risk of miscarriage.

Until recently, providers routinely offered diagnostic tests, rather then screening tests, to women over age 35 because they have increased risk of having a baby with chromosomal birth defects. However, ACOG now recommends that providers offer women over age 35 the option of having a screening test to evaluate their risk before deciding whether or not to go ahead with amniocentesis or CVS (6).

Does the risk of miscarriage increase as a woman gets older?
Most miscarriages occur in the first trimester for women of all ages. The risk of miscarriage increases with age. Studies suggest that about 10 percent of recognized pregnancies for women in their 20s end in miscarriage (1). The risk rises to (1):

• About 20 percent at ages 35 to 39
• About 35 percent at ages 40 to 44
• More than 50 percent by age 45

The age-related increased risk of miscarriage is caused, at least in part, by increases in chromosomal abnormalities.

Can preexisting health conditions affect pregnancy?
Women over age 35 are more likely than younger women to have a health condition that began before pregnancy. Some health conditions, such as high blood pressure, diabetes, and kidney and heart problems, can affect pregnancy. For example, poorly controlled diabetes can contribute to birth defects and miscarriage, and poorly controlled high blood pressure can slow fetal growth.

At any age, a woman should see her health care provider before trying to conceive. A preconception visit helps ensure that she is in the best possible health before getting pregnant. A preconception visit is especially important if a woman has a chronic health condition. Her provider can treat the condition and make any necessary changes in her medications to help assure that she has a healthy pregnancy. The provider also can recommend that a woman take a daily multivitamin containing 400 micrograms of folic acid to help prevent certain birth defects of the brain and spinal cord (neural tube defects).

Are women over age 35 more likely to have pregnancy complications?
Women in their late 30s and 40s are very likely to have a healthy baby. However, they may face more complications along the way than younger women.

Some complications that are more common in women over 35 include:

• Gestational diabetes: This form of diabetes develops for the first time during pregnancy. Studies suggest that women over age 35 are about twice as likely as younger women to develop gestational diabetes (7, 8). Women with gestational diabetes are more likely to have a very large baby who is at risk of injuries during delivery and of newborn health problems (such as breathing problems).
• High blood pressure: As with diabetes, high blood pressure can develop for the first time during pregnancy. This is called pregnancy-induced high blood pressure or pregnancy-induced hypertension. In its more severe form, it is called preeclampsia. Some studies have found that pregnancy-induced high blood pressure is more common in women over age 35 (8, 9).
• Placental problems: The most common placental problem is placenta previa, in which the placenta covers part or all of the uterine opening (cervix). One study found that women in their late 30s were almost twice as likely, and women in their 40s nearly three times as likely, as younger women to have this complication (7). Placenta previa can cause severe bleeding during delivery, which can endanger mother and baby. A cesarean birth (also called c-section) often can prevent serious complications.
• Premature birth: Women ages 40 and older are more likely than women in their 20s and 30s to deliver prematurely (before 37 completed weeks of pregnancy). From 2003 to 2005, 16.6 percent of women ages 40 and older delivered prematurely, compared to 12.5 percent of women ages 30 to 39, and 11.9 percent of women ages 20 to 29 (10). Premature babies are at increased risk of health problems in the newborn period and of lasting disabilities. Some studies also suggest that women in their 40s may be at increased risk of having a low-birthweight baby (less than 5½ pounds) (7, 8). (Low birthweight can result from premature birth, poor growth before birth or both.)
• Stillbirth: Stillbirth is the death of the fetus after 20 weeks of pregnancy. A number of studies have found that women over age 40 are about two to three times as likely as women in their 20s to have a stillborn baby (7, 11). The causes of stillbirth in the over-40 age group are not known.

Are women over 35 more likely than younger women to have a c-section?
The chances of having a c-section increase with age. Mothers over age 40 appear to be more than twice as likely as mothers under age 20 to have a c-section (5). In 2006, according to the Centers for Disease Control and Prevention (CDC), about 47 percent of mothers over age 40, 41 percent between ages 35 and 39, 27 percent between ages 20 and 24, and 22 percent under age 20 had a c-section (5).

How can a pregnant woman reduce her risks of pregnancy complications?
Today, most women in their late 30s and 40s can look forward to healthy pregnancies. Women of all ages can improve their chances of having a healthy pregnancy if they:

• Have a preconception checkup with a health care provider.
• Get early and regular prenatal care.
• Take a multivitamin containing 400 micrograms of folic acid daily, starting before pregnancy and in early pregnancy, to help prevent neural tube defects.
• Begin pregnancy at a healthy weight (not too heavy or too thin).
• Don't drink alcohol.
• Don't smoke and stay away from secondhand smoke.
• Don't use any drug, even over-the-counter medications or herbs, unless recommended by a health care provider who knows they are pregnant.
• Eat healthy foods, including foods containing folic acid and folate (the form of folic acid that occurs naturally in foods). Good sources of folate are fortified breakfast cereals, enriched grain products, beans, leafy green vegetables and orange juice.
• Don't eat undercooked meat or change a cat’s litter box. Both are possible sources of toxoplasmosis, an infection that can cause birth defects.
• Don't eat fish that can be high in mercury, like shark, swordfish, king mackerel or tilefish. Limit albacore (white) tuna to 6 ounces or less a week. Women can safely eat up to 12 ounces per week of fish that have small amounts of mercury, including shrimp, salmon, pollock, catfish and canned light tuna. They also should check with their local health department before eating any fish caught in local waters.
• Get tested for immunity to rubella (German measles) and chickenpox before becoming pregnant and consider being vaccinated if not immune. After being vaccinated, a woman should wait 1 month before getting pregnant.

References

1. American Society for Reproductive Medicine (ASRM). Age and Fertility: A Guide for Patients. ASRM, Birmingham, AL, 2003, accessed 2/5/09.
2. Dunson, D.B., et al. Increased Infertility With Age in Men and Women. Obstetrics and Gynecology, volume 103, number 1, January 2004, pages 51-56.
3. American College of Obstetricians and Gynecologists (ACOG). Age-Related Fertility Decline. ACOG Committee Opinion, number 413, August 2008.
4. Fong, S. and McGovern, P. How Does Age Affect Fertility? Contemporary Ob/Gyn, April 2004, pages 37-46.
5. Martin, J. A., et al. Births: Final Data for 2006. National Vital Statistics Report, volume 57, number 7, January 7, 2009.
6. American College of Obstetricians and Gynecologists (ACOG). Screening for Fetal Chromosomal Abnormalities. ACOG Practice Bulletin, number 77, January 2007, reaffirmed 2008.
7. Cleary-Goldman, J., et al. Impact of Maternal Age on Obstetric Outcome. Obstetrics and Gynecology, volume 105, number 5, May 2005, pages 983-990.
8. Joseph, K.S., et al. The Perinatal Effects of Delayed Childbearing. Obstetrics and Gynecology, volume 105, number 6, June 2005, pages 1410-1418.
9. Usta, I.M. and Nassar, A.H. Advanced Maternal Age. Part I: Obstetric Complications. American Journal of Perinatology, volume 25, number 8, September 2008, pages 521-534.
10. National Center for Health Statistics, final natality data.
11. Bahtiyar, M.O., et al. Stillbirth at Term in Women of Advanced Maternal Age in the United States: When Could the Antenatal Testing Be Initiated? American Journal of Perinatology, volume 25, number 5, May 2008, pages 301-304.

May 2009