"Will my man make a good father of healthy children and will I be as good a mother as my mom?"
"Will I have a healthy baby -- ten toes, ten fingers and a working heart and head?"
"When is the best time to try to make a baby?"
"Will my baby and I be healthier if I see a doctor as soon as I get pregnant?"

Surprise: These questions have environment-related answers. Yes, even, to a degree, whether your "hot" man will make a good father - or, really, a father at all. We've looked at such questions at the National Institute of Environmental Health Sciences. Here at NIEHS, we believe we've learned a lot that can help you with your questions about getting pregnant and the health of your baby-to-be

Q:  "I'd like to have a baby. Should I aim for a particular time of the month for intercourse -- a particular few days in my menstrual cycle?"

A:   It seems funny -- or sad -- that one couple makes a baby the very first time they have sex (whether they want a baby or not) while another couple can try and try for months without getting the child they want so badly.

People trying to have a baby have often been advised to aim for the woman's fertile time midway between her periods. They are told to have intercourse on the day the woman ovulates, or a couple of days before or afterward. Our Institute scientists, taking precise data on more than 200 healthy women trying to have a baby, have determined that you're actually most likely to get pregnant if you have sex the day you ovulate or the five days before.

It seems that a man's sperm may be longer-lasting than some people previously believed, while a woman's ovum, or human egg, disappears more quickly.

Three days after intercourse, there might still be active sperm swimming around that can impregnate and fertilize a newly released egg. But if the sperm is not introduced until after the day of ovulation, a two- or three-day-old egg would be unlikely to still be in good enough shape to be fertilized, even by the freshest of sperm.

You will have a problem, however, knowing when you're five days away from ovulation. There is no test to pinpoint that. A further problem: Your ovulation and fertile "window" - the time when you're likely to get pregnant - can wander around. It's like a moving target.

Older guidelines for getting pregnant assumed that the average woman is fertile between days 10 and 17 of her menstrual cycle. But that's a very rough approximation -- an "average" that may not mean much for you as an individual woman.

Seventeen percent of the women were fertile by day seven of their cycle. Two percent of women were fertile by day four!

Our study also showed very late ovulations occur, even in women who said their cycles were usually regular. Because of these late ovulations, 4 to 6 percent of the women were potentially fertile more than 28 days after the start of their cycle.

In fact, even women who regarded their cycles as "regular" had a 1 to 6 percent probability of being fertile on the day their next period was expected.

Q:  If ovulation times vary widely - and you can't accurately predict them five days ahead of time -- what should a healthy young woman do? How, in other words, should you go about trying to get pregnant?

A:   Well, the director of our NIEHS study, Allen Wilcox, M.D., Ph.D., suggests many couples are best off forgetting about getting the timing "right."

Dr. Wilcox says, "If the average healthy couple wants to get pregnant, they are just as well off to relax and forget "fertile windows" and simply engage in unprotected intercourse at least two or three times over the course of each week."

That's easy-to-follow advice. And you're likely to hit "right" two or more times within the fertile days occurring in each of your cycles.

If you don't conceive the baby you want in a year or so of regular intercourse, talk to your doctor. You may be the one couple in six that has a fertility problem. Simple tests can often pinpoint and help overcome it. The problem can reside in your man about as often as in you, so he will need to be tested too.

At some point, you may be referred to a fertility clinic or specialist. You may be prescribed a drug to trigger ovulation, and your mate's best sperm will be introduced by the doctor at that time. There are other technologies, too - some of them very expensive. There is also some risk of triggering two or more eggs and having a bigger family than you expected.

Q:  "Will my baby and I be healthier if I see a doctor as soon as I get pregnant?"

A:   Certainly, your doctor can increase your chances for a healthy outcome if you see him or her as soon as you're pregnant. But to get the very best odds for yourself and your baby, you should try to see your doctor well before you get pregnant.

Your doctor will have diet and life-style suggestions that should make for a healthier baby, and a healthier you as well. You shouldn't wait until you know you're pregnant to eat well and take vitamins. You should check out what drugs you need to stop to prevent harm to your baby - before you even know you're pregnant. Also, as mentioned, seeing that you are having trouble getting pregnant, your doctor can help with tests and suggestions that fit your situation.

Even with the best of care, there are hazards ahead.

In an NIEHS study of healthy women who wanted a baby, about one in five fertilized eggs failed to survive six weeks. That would be before you and/or your doctor even would know you are pregnant. It may be Nature's way of sparing a mother the burden of carrying an embryo that cannot survive. Further along in pregnancy, a much smaller number of additional fetuses are lost in spontaneous miscarriages. That's always sad, but 95 percent of the women losing a fetus in the study got pregnant within two years afterward.

Most women's miscarriages, like most birth defects, have no clear cause. But genetic defects have been seen in some lost fetuses. Surely, the environment also plays a role, just as it does in the birth of preemies - early, underweight infants. (The newborns of smokers, for example, are more likely to be born prematurely than the newborns of non-smokers.)

Q:  "How do the things I eat and do affect my child?"

A:   What you eat, drink and do during pregnancy and just before pregnancy is vital to your child because, for nine months, your body is your child's environment. Your circulatory system feeds nutrients to your unborn child's system through an organ, called the placenta. Your circulatory system also removes waste materials from your child via this organ, which is attached to the wall of your uterus and to the bellybutton of your baby.

We used to think that the placenta kept poisons from reaching the unborn child. That popular idea was dealt a death blow in the late 1950's and early 1960's, when many women took a sedative called thalidomide which caused hundreds of children to be born with flipper-like limbs where their arms and legs should be.

Then in 1971, after it was prescribed for more than 20 years to try to prevent miscarriages, diethylstilbestrol, or DES, was found to have produced rare cancers and reproductive abnormalities in "DES daughters," the daughters born to the women being treated. (At NIEHS, we did some of the research that showed DES' adverse effects. Later, in test animals, NIEHS scientist Retha R. Newbold also found that harm may extend to "DES granddaughters" and to "DES grandsons.")

Illegal or "recreational" drugs are risky, too. Cocaine's use during pregnancy has been shown to increase malformations of the urinary tract five-fold. There are also risks of low birth weight, miscarriage, brain damage and fetal death.

Because the dangers have been publicized, many women who get pregnant know to stay away from illegal drugs, and from many nonprescription and prescription drugs as well.

If you've ever taken Accutane (isotretinoin) for very severe acne, you know this drug is an extremely strong cause of gross birth defects. Before taking this drug you must have a test to show you are not pregnant. Then you must take birth control measures beginning a month before you start the acne drug, throughout the treatment period and, because of its persistent effect, for a month after you stop.

Drugs to treat cancer, such as methotrexate, also cause birth defects - and pregnancy should likewise be avoided when getting such treatment.

Even aspirin carries a risk of bleeding complications for mother and child, but it may be prescribed by a doctor under certain conditions.

Thus, the best advice to pregnant women (or women who may become pregnant) is: Ask your physician before taking any prescription or non-prescription drug, including herbal medicines and other "natural" therapies.

But don't panic unnecessarily. Some drugs have been used in pregnant women for a long time without doctors observing any problems.

If you need a drug to control high blood pressure, asthma, lupus or other chronic problems, don't stop the moment you find you're pregnant. Talk the situation over with your doctor first. Talking it over with your doctor before you become pregnant is even better, since the fetus may be particularly susceptible to injury at its early stages, before you even know you're pregnant.

Epileptic? A pregnant woman's seizures can cause damage to the unborn baby's brain. Thus, women with epilepsy and their doctors usually decide that continuing the medication that controls the seizure is the path of less risk.

There's a similar trade-off for women who must take insulin daily to control their diabetes. They are several times as likely to have a baby with a major defect. However, if a woman stops her insulin, neither she nor her unborn infant may survive. That's another reason to see a doctor before conceiving a baby -- yet only about one woman in four does so.

Increasingly, we are seeing that our unborn babies can also be hurt by what we eat (or don't eat), what substances we handle at work, at home and in the farm or garden, as well as many other environmental factors. Some of these substances can subtly influence the IQ, health, development and motor skills of children still to be born - still, in some case, to be conceived.

For example, lead may be passed along. It can accumulate in the bones of a young girl exposed to it and be released, years later, exposing her unborn child. The lead can lower the child's IQ. One study shows lead may even contribute to a child's chances of getting into trouble with the law.

A mother's exposure to mercury can delay her child's development. That may also be true of PCBs, still another NIEHS study suggests. There are undoubtedly other chemicals, metals and other exposures that also produce such effects.

Harm can also result from deficiencies -- from substances a pregnant woman fails to get. If you have been eating a diet without sufficient folate or folic acid, a B vitamin found in green leafy vegetables, when you become pregnant there is a greater risk of deformities called neural tube defects of the brain and nervous systems. In these defects, the infant may fail to develop a brain or, more commonly, the spinal column may fail to close around and protect the spinal cord. Without this protection, the baby's spinal cord may be injured during the upheaval of birth so that the baby may be partially, but permanently, paralyzed.

The Food and Drug Administration now requires that rice and flour products be fortified with folate. It is difficult to get enough from an ordinary diet otherwise. Even with the fortification, government experts and others advise all women of child-bearing age - that is, girls and women from puberty through menopause - to take an ordinary, folate-containing multiple vitamin pill each day. Taking folate after pregnancy starts is not as effective.

In other ways, too, good nutrition when you make your baby may be more important than we generally think. Studies of women giving birth during World War II showed that women who conceived when near starvation were more likely to have babies with malformations than women at near-starvation when they delivered.

The idea that a pregnant woman is eating for two is true. In some cases, Nature may favor the child. The mother's bones and general health suffer. In other situations, the baby or both mother and child are affected. Talk to your doctor or nurse-midwife about a good pregnancy diet. "Eating for two" does not mean eating twice as much but getting the appropriate amount of nutrition for both you and your unborn child.

Q:  "Will my man make a good father of healthy children - and will I be as good a mother as my Mom was?"

A:   You can both be fine parents of fine children -- especially if you make sure your environment is free of harmful exposures.

Remarkably, each tiny, one-celled egg or ovum that you produce every month or so has actually been within your body since you yourself were born! As a result, some scientists speculate that environmental influences might impact on those ova at any time over the years they are being carried -- in other words, at any time over your lifetime.

Though sperm are produced "fresh," fathers-to-be aren't off the hook either. Whereas women used to be more likely to be blamed, the causes of childlessness are now broken down more evenly - about 50/50.

Environmental influences, such as vitamin status, radiation, drugs, diseases, and occupational exposures, can influence the quantity and quality of a man's sperm. Such exposures can also prevent a man from getting or maintaining an erection. So it isn't "unmanly" for industrial, medical and agricultural workers to take advantage of lead shields, protective masks and clothing, and after-work showers. Quite the reverse.

Infections, such as mumps, are well-known causes of male infertility, but pesticides and other chemicals can present a risk of infertility and birth defects. These defects may occur if a damaged sperm fertilizes an egg and the egg does not develop properly. The result may be a miscarriage or a potential health problem in the baby later on.

Men and women may track in lead dust from building sites where old, lead-painted buildings have been knocked down, contaminating their homes and exposing their families.

Farm workers risk problems for themselves and their families if they needlessly go into recently sprayed fields and/or don't wear long-sleeved shirts and other clothing that covers their skin. Family exposures can be minimized if workers strip off contaminated clothes at work or as soon as they return home, and the clothes are promptly washed - separately from other clothes. The exposed workers themselves should also shower promptly.

We all also have habits, good and band. You may also be interested in some NIEHS work that suggests that the old habit of female douching reduces fertility -- as may too much coffee.

Alcohol can be harmful. It is regarded by the March of Dimes as the leading cause of preventable mental retardation, as well as the most common known cause of fetal damage. Major physical and mental problems occur in the children of drinking women, especially those who use alcohol a lot. Many doctors recommend you avoid all alcoholic drinks during pregnancy.

Women born with a birth defect themselves often worry that their children will be similarly affected. Working with Norwegian scientists, we studied this risk among a half-million Norwegian women (born with defects between 1967 and 1982) and their offspring. Less than 4 percent of the offspring turned out to have birth defects - and generally only at the same level of risk as other women's children. The only significant increase in risk was for having the same defect as the mother's. (In a follow-up study, the offspring of men who had been born with birth defects proved to have an increased risk of the same defect, compared to other men's children, plus an increase in other birth defects as well.)

Tips

You wouldn't expect this discussion to end without some do's and don'ts, would you? So here (at the risk of a little repetition) are some environmental tips if you are of child-bearing age -- from your teen years to menopause:

• You should not eat swordfish, shark, king mackerel or tilefish while you are pregnant or can become pregnant. These large, long-lived ocean fish accumulate mercury pollution as they eat smaller fish. If you then eat these fish, the mercury can accumulate in you and hurt the development of nervous system of your unborn child. The Food and Drug Administration also advises you not to eat these big fish when you're nursing a baby - and not to fee these fish to small children.
  
  
• Eat plenty of green, leafy vegetables AND swallow a multi-vitamin containing folate, or folic acid, (a B vitamin) every day, before and during pregnancy.
  
  
• Avoid soft cheeses. Those delicious brie and Roquefort cheeses, particularly those famous unpasteurized products, are easily contaminated by a tough bacteria called Listeria. Ordinarily, people are not much affected by Listeria, but in pregnant women the bacteria then can cause violent vomiting, flu-like symptoms and loss of your unborn child. This loss can occur even before you know you're pregnant.
  
  Mexican-style soft cheeses such as queso blanco, queso fresco, queso de hoja, queso de crema and asadero are susceptible, as are such other soft cheeses as feta, or goat cheese, brie, Camembert and blue-veined cheeses such as Roquefort. The Food and Drug Administration recommends that pregnant or potentially pregnant women should instead eat hard cheeses made from pasteurized milk or marked as aged for 60 days or longer.
  
  
• Take care with all foods. To reduce food poisoning risks, FDA also recommends 1) thoroughly heating meats purchased at deli counters, whether cured (like salami) or not, before you eat them; 2) washing fruits and vegetables with water, 3) keeping your refrigerator, counter top and utensils clean; 4) washing your hands and utensils with warm soapy water after contact with raw foods, especially raw meats, and 5) cooking meat, poultry and seafood thoroughly. Follow "use by" dates and other instructions for refrigerating foods.
  
  To err on the side of caution, some environmental health experts suggest that pregnant women - despite those infamous cravings we are supposed to get - avoid overdoing any single food or beverage in the diet. Varying your diet guards you against getting a massive dose of a problem substance, if there should be an accident that unexpectedly contaminates a particular food.
  
  
• Beware raw meat - and your cat. They may harbor a parasite that causes toxoplasmosis. If you get it while pregnant, your unborn child has about a 40 percent chance of contracting it too. In early pregnancy, this can cause the child to be blind, deaf and mentally retarded.
  
  The parasite can be found in cat feces, soil and infected meats that have not been thoroughly cooked. Cats get it from eating infected birds, mice and rats. So keep your family cat indoors to reduce its chances of getting the parasite - and have someone else clean its litter box, so that you don't get it.
  
  
• Protect yourself from pesticides and other chemical exposures. We don't know enough about the safety of home and occupational pesticides and chemicals in pregnancy. So it is a good idea to be cautious. Ask your employer to give you copies of Material Safety Data Sheets (MSDSs) for any hazardous materials in your work, as required. A few substances of concern are lead, carbaryl (Sevin), bromine vapor, carbon disulfide, ethylene dibromide, mercury vapor and styrene and acetone used in plastic production.
  
  Use farm and industrial materials with caution, following all the precautions on the label.
  
  You can be exposed to chemicals in the air you breath, through your eyes, or in your food and water. So store chemicals in sealed containers when not in use, follow recommendations for ventilation. A major route of contamination is through your skin, so wear protective clothing and gloves. Wash off any spilled materials immediately. Wash your hands before eating, drinking or smoking.
  
  If you are a farm worker, factory worker or scientist, or you have one as a husband, partner or family member, you and/or that other worker should shower at work at closing time or as soon as you/they get home. Clothes contaminated by pesticides, chemicals or metals should be washed at work, if possible. If they must be washed at home, they should be washed separately from other clothes, and as soon as possible.
  
  If you are a dentist, dental assistant or hygienist or work with the anesthetic nitrous oxide (N2O) in human or veterinary medicine, you should know be cautious because this gas has been shown to cause defects in the offspring of exposed lab animals. Adequate ventilation, tests for leaks and other guidelines should be followed to limit your exposure. Women working as potters, with solder, or as home remodelers may encounter lead, which has been associated with miscarriages, stillbirths and infertility for more than 100 years. The National Institute of Occupational Safety and Health also warns of reproductive problems among women viscose rayon workers exposed to carbon disulfide (CS2) and among electronic and semi-conductor workers exposed to ethylene glycol ethers such as 2EE and 2ME.
  
  And if you're planning to decorate a room as a nursery, why not ask a pro or a partner to do the painting (while you go elsewhere and avoid the fumes.)
  
  
• Avoid smoke, as well as smoking. Smoking increases the risks of an underweight baby and of stillbirth, the birth of a dead fetus. Smoking and also passive smoke exposure may double the risk of a rare but devastating condition called persistent pulmonary hypertension of the newborn. In this condition, infants starve for oxygen because blood is not pumped through the lungs to the body but continues to flow as it did before birth and the activation of the lungs. Without successful surgery to correct the flow, the infant may die. Babies born to women who smoked during pregnancy are also more likely to have asthma and other respiratory problems. They also are more likely to die of sudden infant death syndrome - SIDS. SIDS reduction campaigns emphasize positioning infants on their backs for sleeping as well as keeping cigarette, cigar and pipe smoke away.
  
  
• Avoid x-rays, hot tubs and saunas. They pose environmental risks for pregnant women. If x-rays are needed for medical reasons, your doctor will shield your abdomen (and thereby your fetus) from the rays. The March of Dimes also suggests pregnant women try to avoid infections. Rubella (German measles) during pregnancy can cause ear, eye and heart abnormalities. You can be tested to see if you've been exposed and are immune. If not, you can get vaccinated - but then should wait three months before getting pregnant. For avoiding many infections, frequent hand-washing can help.
  
  
• Stay faithful to one, uninfected and equally faithful partner to prevent the tragic consequences of a new-born with HIV or other sexually transmitted diseases. Discuss your own and your mate's sexual history (and any injected drug use) with your physician - and get tested for HIV or other infections, as appropriate. Even if you have HIV, for example, proper drug treatment can often prevent your child from becoming infected.
  
  
• Exercise moderately. Walk, swim, ride a stationary bike and/or join in a special prenatal aerobics class three or more times a week. Even a vigorous workout is ok for most women and may help you carry your baby to full term. Not so advisable: bouncing or jerking movements, toe touches, knee bends and sit-ups. Doctors generally counsel against any vigorous exercise that has you lying on your back after the first three months of pregnancy. Injury-risking sports - skiing, rock-climbing, horseback riding - aren't good bets. But regular, safe exercise can make labor easier and prepare you to get back in shape afterwards.
  
  
• Relax, too. You don't need a lot of stress during pregnancy, or before pregnancy either! Summing up, you just need a good clean, healthy and uninfected man; a doctor; a good diet; a vitamin pill, and a work and home environment where you won't be needlessly exposed to tobacco smoke, pesticides, alcohol and other potentially harmful chemicals, drugs, mercury, soft cheese, undercooked meats and kitty litter.
  
  

Sources:

• The fertile window in the menstrual cycle, BMJ Vol. 321:1259-1262, Wilcox AJ, Dunson DB, Baird DD.
• Time of implantation and loss of pregnancy. New Engl J Med 340:1796-9, 1999, Wilcox AJ, Baird DD, Weinberg CR.
• Timing of sexual intercourse in relation to ovulation. New Engl J Med 333:1517-21, 1995, Wilcox AJ, Weinberg CR, Baird DD.
• Incidence of early loss of pregnancy, N Engl J Med 319(4): 189-94, 1988, Wilcox AJ, Weinberg CR, O'Connor JF, Baird DD, Schlatterer JP, Canfield RE, Armstrong EG, Nisula BC
• Reduced fertility in female mice exposed transplacentally to DES, Fertility and Sterility 1982; 38:364-371, McLachlan JA, Newbold RR, Shaw HC, Hogan M and Dixon RL.
• Long-term effects on the female mouse genital tract associated with prenatal diethylstilbestrol, Cancer Res 1980:3988-3999, McLachlan JA, Newbold RR and Bullock BC.
• Proliferative lesions and reproductive tract tumors in male descendants of mice exposed developmentally to DES, Carcinogenesis, 2000; 21:7:1355-63, Newbold RR, Hanson RB, Jefferson WN, Bullock BC, Haseman J and McLachlan JA.
• US Food and Drug Administration; March of Dimes.

NIH Publication #01-4966

 Additional Information:

• NIEHS/National Toxicology Program: Center for the Evaluation of Risks to Human Reproduction
• NIEHS Health Topic: Reproduction, Reproductive Health, Reproductive Toxicology
• NICHD Publications: Health Information and Media

This publication was written and developed by William Grigg, with layout of the printed version done by Catalone Design Co. Single copies of the printed version are available by sending e-mail to booklet@niehs.nih.gov or by calling 919/541-3345