Researchers from New York University found that a cavity-causing bacterium that grows on tooth surfaces appeared much earlier in babies delivered by C-section than in those delivered vaginally. The study evaluated 156 mother-infant pairs.
"We are the first to report that there is a link between C-sections and the acquisition of cavity-causing bacteria in the baby," said Dr. Yihong Li, an associate professor of basic science and craniofacial biology at the New York University College of Dentistry.
Li, who is lead author of the study, added that the researchers did not study whether the babies delivered by C-section actually got more cavities later, but only that they had more cavity-causing bacterium earlier.
The study appears in the September issue of the Journal of Dental Research.
The reason for the findings? Li suspects that vaginally delivered infants, because of exposure to a greater variety and intensity of bacteria from their mothers and the surrounding environment at birth, develop more resistance to the cavity-causing germ than do C-section babies, who have less bacterial exposure at birth.
The women in the study were mostly black women from an inner-city area of Birmingham, Ala. In all, 127 of the women had vaginal deliveries and 29 had C-sections. Their mean age was approximately 21 years, and about 75 percent of the women had cavities. Li and her team then started collecting saliva and plaque samples from the babies to evaluate them for bacterium.
The bacterium, Streptococcus mutans, was detected in 55 of the 156 infants, on average at 22.3 months of age. But the C-section infants acquired the germ at 17.1 months of age, compared to 28.8 for the vaginally delivered babies.
Dr. Edmond Hewlett, an associate professor of dentistry at the University of California, Los Angeles School of Dentistry and a consumer advisor for the American Dental Association, called the study sound.
"What's new here is the association between the time of infection with bacteria that cause cavities and the type of delivery," he said. It has been known that the primary route of infection for cavity-causing bacteria is mother to infant, he said.
Even so, the new study findings "shouldn't affect the decision for women to have a C-section," Hewlett added.
The take-home message for mothers, Li said, is this: "If the mother has very poor oral health, she really needs to pay attention to her [baby's oral health] if she delivers C-section."
"Don't share spoons with your baby," Hewlett tells mothers, especially those who have cavities. "Chewing gum with Xylitol in it after eating is a good way to clear the mouth of bacteria."
More information
To learn more about preventing cavities, visit the American Dental Association.
Today, the same exercise recommendations that apply to most of the rest of the country -- 30 minutes or more of moderate exercise on most if not all days of the week -- also apply to pregnant women, if they are in relatively good health and their doctors approve.
"It's good for pregnant women to exercise if they would like to do so," said Dr. Richard P. Frieder, a clinical instructor of obstetrics and gynecology at the University of California, Los Angeles, and an obstetrician-gynecologist at Santa Monica UCLA Medical Center.
"Generally women feel better and are fitter if they exercise during pregnancy," Frieder added.
But he cautioned that pregnant women shouldn't expect miracles from exercise: "It doesn't make labor any easier," he said. "That's a marketing myth that sells exercise classes."
Physical activity during pregnancy does have benefits, however. It may help with weight control, allowing the mom-to-be to avoid too much weight gain during pregnancy.
And a regular workout may help a woman avoid pregnancy-related health risks, said pregnancy expert Michelle Williams of the University of Washington, Seattle.
In her research, Williams has found that physical activity during pregnancy reduced the risk of gestational diabetes by half, and the risk of pre-eclampsia -- a potentially dangerous condition marked by high blood pressure and other problems -- by 35 percent.
"The most common exercises were walking and jogging and aerobics. Even stair-climbing as part of a daily active lifestyle was associated with reduced risk of pre-eclampsia," said Williams, who is also associate director of the Center for Perinatal Studies at Swedish Medical Center, in Seattle.
"On the basis of our data, we can say that any activity is better than no activity. Much more research is needed to determine the optimal 'dose' amount, frequency and type of activity that is associated with the best pregnancy outcomes," she said.
Another study by researchers at the University of North Texas found that Cesarean delivery was 4.5 times more likely for sedentary women than for active women. The researchers compared 93 non-exercising women with 44 active women.
The American College of Obstetricians and Gynecologists issued revised recommendations for exercise during pregnancy. The guidelines say that while participation in a wide range of activities appears to be safe, each activity should be reviewed by a woman's doctor for potential risk.
According to the American Academy of Family Physicians, the most comfortable exercises during pregnancy are those that don't require you to bear extra weight, such as swimming and stationary cycling. Walking and low-impact aerobics are other good choices. Women should consult with their doctor about the best exercise.
If you didn't exercise before pregnancy, the advice to get individual instruction about exercise is especially crucial.
As the pregnancy progresses, "listen to your body," Frieder tells his patients. "Make allowances for tiredness. Don't exercise at the level you are used to if you are too tired."
Be sure your heart rate is lower than 140 beats per minutes, he said. And drink plenty of fluids before and after your workout.
Avoid exercise on extremely hot or humid days. And stop a workout if you have pain, bleeding or faintness or other symptoms -- and call you doctor.
Also, be aware that your center of gravity is lower during pregnancy and that may affect your ability to do exercises that seemed easy before. And your ligaments and joints are looser and more flexible when pregnant, so you're more likely to get sprains and strains.
More information
To learn more about exercise and pregnancy, visit the American Academy of Family Physicians.
