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

 

A: What you eat, drink, and do during 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 1950s and early 1960s, when many women took a sedative called thalidomide that 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.

 

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 – or even yet 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 begins 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.