QUESTION: We are trying to get pregnant, but my husband and I are wondering about coffee consumption. I am 25 and in very good health. I have about two cups of coffee in the morning, and no more caffeine throughout the day. I assume that caffeine is the issue with coffee. I will cut back on the coffee if needed. What is the latest concerning coffee and caffeine during pregnancy?
M.R., Jacksonville, Fla.
ANSWER: The coffee/caffeine debate maintains a life of its own. (You are correct that caffeine is the key.) In a healthy person, the half-life of caffeine is about three to four hours. That's the time it takes the body to reduce the blood level to half by changing the caffeine into other substances.
The half-life rises for pregnant women, going up to about 15 hours during the last trimester. The concern is that caffeine is able to cross the placenta, and the developing fetus lacks the ability to metabolize it. Studies have offered evidence on both sides of the risk argument.
One study indicates that having more than three cups a day can significantly affect your ability to conceive, but another finds no such association.
The association between coffee consumption and the risk of miscarriage is another issue. A study in the January 2008 issue of Epidemiology looked at intakes of up to 200 milligrams per day and concluded that there was little risk. (This is about as much caffeine as there is in 1 1/2 to 2 cups of coffee, depending on the strength of the brew.)
However, we also have a study in the January American Journal of Obstetrics and Gynecology that reported an adjusted hazard ratio 1.42 from caffeine intakes up to 200 milligrams per day. (A hazard ratio of 1.0 means no effect; the higher the number, the more significant the effect.) The adjusted hazard ratio for intakes of 200 milligrams or more per day was 2.23, which is more than double the risk.
A study in the January 1998 issue of Archives of Diseases of Children found an association between heavy coffee drinking during pregnancy (defined as over 4 cups a day) and the risk of sudden infant death syndrome (SIDS).
While there are studies on all sides of the issues, there seems to be little information to condemn light coffee consumption – up to one cup a day.
One thing, however, rings true – that coffee is not essential for the health of your child. Couple this with the fact that there is no guaranteed safe level of intake. Science, after all, makes mistakes. Of all the times in life, pregnancy is not the time to take risks. It would be best to eliminate caffeine or at least keep it to an absolute minimum. Why not err on the side of safety?
Does sunscreen prevent the absorption of vitamin D? I walk daily for about 30 minutes, but depending on the weather, I am covered with a light sweater or sunscreen. I am over 60 and take a calcium supplement with 400 IU of vitamin D. Am I getting any vitamin D from my daily exposure, or should I be taking more in a supplement?
P.R.
Sunscreens come in various strengths, but in general they are designed to prevent ultraviolet rays from penetrating your skin, which is necessary for the body to make its own vitamin D. You seem to have your vitamin D covered, having that supplement in addition to whatever is in your diet. The National Institutes of Health has an information page on vitamin D at tinyurl.com/dfy38.
