When my son Robert was just a few days old, I took him for a routine visit to his pediatrician. In addition to ordinary questions about my baby, I had some pressing queries about myself, including : Can I continue my morning wake-up cup of coffee now that I'm breast-feeding?

The pediatrician clearly didn't like the idea.

"I can tell when Mom's had a big latte from Starbucks," she said. "The baby's heart rate goes way up."

How about alcohol, for my glass of wine at night?

"What!? This baby is a couple of days old and you're asking me if you can have a drink? Absolutely not."

"What about when he's older?"

"Maybe in a few months, when he's sleeping through the night, you can have an occasional glass of wine late at night after your last nursing."

But in general she was clearly against alcohol and caffeine for breast-feeding moms.

This advice confused me, since numerous books and articles in parenting magazines said that an occasional alcoholic drink or cup of coffee was acceptable. In fact, my obstetrician/gynecologist had told me she sometimes recommended that women have a glass of wine while nursing to help them relax.

From doctors to parenting magazines to books to the buzz around the block, there seemed to be no consensus about the effects of alcohol and caffeine that babies might receive through breast milk. It was another example of the sort of medical advice about which experts are deeply divided, yet none seem able to justify except by the sort of anecdotal observation that they reject from others.

Determined to get to the bottom of the issue, I set out to delve into the scientific studies, find the best researchers and seek the answers so many breast-feeding moms want: Can we have our morning cup of coffee? Can we have an occasional glass of wine?

Tracking the Truth

Searching for an authoritative source to start with, I called Joan Younger Meek, editor-in-chief of the new American Academy of Pediatrics book "New Mother's Guide to Breastfeeding." Meek, a pediatrician with Orlando Regional Health Care in Florida, was quite clear.

"Alcohol is not contraindicated during breast-feeding," Meek said. "For those women who do drink, a drink or two several times a week is fine."

Meek said alcohol passes easily and quickly into the breast milk. But, depending on a number of factors (how fast Mom downs the drink, how much food she consumes with it, how large she is, how rapid her metabolic rate), the alcohol passes back out of the milk and gets reabsorbed into her circulation. The alcohol reaches its peak level in the milk within 30 to 90 minutes, and clears the milk in an average of two to three hours per drink. Pumping out breast milk does not remove the alcohol any faster.

While Meek said it is acceptable to breast-feed as long as sufficient time has passed since the mother has had a drink, she warned that there are serious concerns about the effects of long-term heavy consumption of alcohol on nursing babies. Studies in animals show that over time, high alcohol consumption may cause a decrease in the hormones that regulate the mother's breast-feeding. Large doses of alcohol via breast milk can cause lethargy, drowsiness and decreased weight gain in babies.

So: By Meek's advice, a little alcohol is okay, just not within a couple of hours before breast-feeding.

What about the caffeine?

"Caffeine also in moderation is fine," Meek said. "There really shouldn't be any prohibition on caffeine. It will vary from baby to baby."

Caffeine also passes into the mother's milk, reaching peak level in an hour. Studies show that caffeine is detected in an infant's blood only if the mother has digested a significant amount of it. Still, doctors (and moms) have noticed that some breast-fed babies become irritable and have trouble sleeping when their moms' drinks contain caffeine.

Regarding her more liberal recommendations, Meek said, years of research have shown benefit after benefit of breast-feeding for babies, and she worries that if doctors set too many limits on women, they won't breast-feed at all.

"Unless Mom is overdoing something, it's not going to be a problem during lactation. But if we make all these rules, the mothers are going to say it's not worth it to try to breast-feed."

An interesting start -- and useful, because it seemed to permit me to do what I was inclined to do anyway -- but I wanted to know more. I began searching PubMed, the National Library of Medicine's medical database. The name that emerged most frequently regarding alcohol and breast-feeding was Julie Mennella.

Alcohol on Baby's Breath

I reached Mennella at the Monell Chemical Senses Center in Philadelphia. Mennella, a biopsychologist, said she had originally been interested in whether alcohol would flavor breast milk and, if so, how babies would respond. She noticed that thousands of years of folklore supported the idea that alcohol benefited lactation. But since she didn't find any good research to back it up, she decided to do some of her own.

With fellow researchers, Mennella recruited 12 nursing women. They tested the women on two occasions a week apart -- one week the women drank orange juice mixed with alcohol before nursing their babies, and the other they drank plain orange juice.

The women pumped out small samples of milk 30 minutes, one hour, two hours and three hours after drinking. Researchers measured the alcohol concentration in the pumped milk and had adults smell the milk to see if they could tell the difference.

Mennella's research revealed that not only did the alcohol seem to flavor the milk -- adults could smell it -- but also that the babies drank an average of 20 percent less milk in the three to four hours after their mothers drank the alcohol-laced orange juice than they did after the no-alcohol sessions. (To measure consumption, the babies were weighed before and after feeding.) The alcohol also seemed to disrupt the babies' sleep patterns. Mennella published her results in a 1991 New England Journal of Medicine (NEJM) article, and the study caused a stir and some controversy.

Mennella conducted further studies showing that the reason for the drop in milk intake was not that the infants didn't like the taste, sucked less frequently or drank for less time. She is convinced that women produce less milk after drinking alcohol. She thinks alcohol affects the hormones that control breast-feeding and currently is testing her hypothesis in a study at the University of Pennsylvania.

Mennella's work shows the possible effects of alcohol on mother's milk and infant behavior -- but what about long-term effects on the baby? The most commonly cited study on this was published in 1989 in the NEJM.

The study of 400 Seattle women revealed that year-old infants breast-fed by mothers who downed one alcoholic drink or more daily for the baby's first year showed decreased motor development but normal mental development. The scores of infants of breast-feeding mothers who drank less than one drink per day did not differ from those whose mothers did not drink at all.

That result alone may be enough to convince me, as it likely has many women, to cut out the glass of wine with the steak on Friday nights. But it's not the end of the story.

Last year, researchers replicated the Seattle study with a group of 915 women in England.

They got contradictory results: The babies of women who drank moderate amounts of alcohol during lactation did better in the motor skills tests than the babies of mothers who did not drink at all.

I asked Jean Golding, one of the English study's authors, to speculate about why the results were so different.

Golding, a professor of pediatric and perinatal epidemiology with the Department of Child Health at the University of Bristol, said, "Our study was bigger than the original study, but it's also on a different continent with possibly different genetic backgrounds, so there may be different effects in different population groups," Golding said.

In the published results of the English findings, the authors speculated that further research involving older children might help resolve the two studies' apparent conflicts.

"Really, the message was that breast milk was so important in the development of the child that alcohol in moderate amounts will not have a negative effect," Golding said. "A little alcohol seemed to do everybody a lot of good."

Help Me, Please

It was becoming clear to me why there is still so much uncertainty about these questions. Equally credible researchers asking slightly different questions have found differing results. I decided I needed someone to help me put the conflicting research into perspective.

Ruth Lawrence has spent a lifetime looking at chemicals in mother's milk. As a professor of pediatrics, obstetrics and gynecology at the University of Rochester's School of Medicine and Dentistry, Lawrence directs the school's Breastfeeding and Human Lactation Study Center. She is also the author of "Breastfeeding: a Guide for the Medical Profession."

Lawrence discourages basing decisions on alcohol and breast-feeding on any one study or researcher and steers me instead toward the 1991 Report on Nutrition During Lactation published by the Institute of Medicine, which is part of the National Academy of Sciences. Lawrence was a member of the committee writing the report, and they reviewed all the available literature on alcohol and lactation.

The report recommends that a breast-feeding woman who is going to drink restrict her alcohol intake to no more about 21/2 ounces of liquor, eight ounces of wine or two cans of beer per day, and says more than that may impair the milk ejection reflex.

Frankly, I'm a little shocked that the report says it's okay for a nursing mom to have that much to drink per day. Of all the pediatricians, books, Web sites and articles I consulted , this is the most permissive amount I've seen. Also, it concerns me that the report is 12 years old. But Lawrence assures me the body of research -- before and since the report -- backs up her recommendation that it's fine to have a glass of wine with dinner or a cocktail at a party. She says she's concerned some people have overreacted to Mennella's and Little's research.

"There's such an issue with alcohol, so we sort of take the stand that it's okay to have a modest amount and let it go at that," Lawrence said. "The reality is that the one time you might have a few minutes to sip some wine is when you are feeding the baby."

Room for Milk in That?

So far I had received no definitive answers on alcohol in breast milk. Maybe it would be easier when it came to the coffee question.

Cheston Berlin is a professor of pediatrics and pharmacology at Penn State Children's Hospital in Hershey, Pa. He has been studying drugs and other chemicals in human milk for more than 20 years, and his research on caffeine and breast milk is often quoted.

Berlin's studies reveal that the amount of caffeine that gets into the mother's milk is less than 1 percent of what the mother ingests. After mothers drank coffee -- as much as six cups a day -- Berlin tested their babies' urine for caffeine but didn't find a measurable amount.

"It's inconceivable to me that the occasional use of a caffeinated beverage is going to pose any danger to a nursing infant," Berlin said.

Great news, but read on, nursing moms, before you head out for that double mocha latte with whip.

Lawrence agrees with Berlin that the amount of caffeine that gets into breast milk is very small, but she said small babies don't handle caffeine well. About 25 years ago, doctors began giving caffeine to infants in intensive care units to help them "remember to breathe." They found it took the babies two weeks to clear the caffeine out of their system. The younger the baby, the longer it took them to clear the caffeine.

So if a mother drinks a lot of caffeine -- three or four cups of coffee throughout a day -- that caffeine can build up in her baby, especially a young one. If the mother continues to drink coffee -- or consume anything else containing caffeine -- she is maintaining her own caffeine levels, and the baby never clears it from his or her system.

"In about six or seven days, the baby will get jittery, and we've had babies admitted to the hospital because of this extreme jitteriness," Lawrence said.

Her recommendation is to avoid nursing the baby for two hours after drinking caffeine to give some of the caffeine time to leave the mother's system. As with alcohol, the amount of caffeine the baby gets and how the child is affected depends on a number of factors, including how much caffeine the mother consumes, how old the baby is, the amount of time between caffeine intake and feeding, and how mother and baby each metabolize caffeine.

A Mixed Beverage

Wondering what my baby's pediatrician would say to all this, I return to her office armed with a stack of medical papers three inches thick and interviews with some of the world's top breast-feeding researchers and experts. Bouncing 7-month-old Robert on my hip, I try to summarize what I've learned.

She seems dubious -- especially when I mention some of the less-than-conservative advice. She pulls out her own books on chemicals in breast milk and starts reading the sections on alcohol and caffeine with me. We look at the literature citations, and I see familiar names: Mennella, Lawrence, Berlin, Little, Golding.

Would she change or amend her earlier recommendations? She's not biting. She cites the paucity of research and says we lack concrete answers. She falls back on one of the most important mantras of doctors : Do No Harm.

"If we know these substances have some physiological effect on the mothers and the babies, why take chances?" she asks.

After all my digging, the totality of the research basically says that a little bit of alcohol or caffeine will probably be okay and that it appears wise to put as much time between those drinks and breast-feeding as possible. There's also a consensus that consuming a lot of either substance during breast-feeding is a really bad idea. And there are a few outliers on each side of the argument -- those who are more permissive, fearing too many rules will discourage women from breast-feeding at all, and the more restrictive, who argue there's no reason to take a chance with your baby's heath.

Not the sort of precision I'd hoped for, but that seemed to be what lay underneath. The one thing that has really shocked me is how little research has actually been done.

Even with all my new knowledge, however, I find that I've come full circle. I'm leaning to the conservative side of the issue. Ultimately I have to trust my maternal instincts and, as all the books advise, make the responsible decisions together with my baby's doctor.

I'll treat myself to an occasional half-cup of coffee in the morning and maybe enjoy a glass of red wine with my husband once in a while after the baby is asleep.

But in the end I find myself agreeing with our pediatrician: Why take any chances?

Elizabeth Agnvall, a former editor of Dallas Child magazine, writes frequently about parenting and health.