That's not the case for all women, she cautions. Those with a condition called placenta previa, in which the placenta covers the opening of the cervix, should abstain because there is a risk that anything penetrating the cervix could cause bleeding from the placenta.
Women at risk for preterm labor are usually told to abstain as well. Most of the studies that have looked at this issue concluded that the chance of sex causing preterm labor was only higher in women who also had a lower genital tract infection. But because such infections can go unnoticed during pregnancy, doctors err on the side of caution and recommend avoiding sex if you are at risk for preterm labor.
Some couples think that sexual intercourse near the end of pregnancy might induce labor. There is good theory behind this popular belief: The hormone released by orgasm, oxytocin, is the same one doctors use to induce labor. In addition, semen contains molecules called prostaglandins, which are also used by doctors inducing labor to help "ripen" the cervix. The few studies examining this question have been inconclusive, Jones says.
"Every doctor has anecdotes of patients who have tried it and went into labor the next day," Jones says. For uncomplicated pregnancies, she says it's safe for couples wanting to kick-start labor to try.
Light drinking of alcohol may be OK
It's well known that moderate, heavy or binge alcohol consumption during pregnancy can lead to fetal alcohol spectrum disorders, which can include facial deformities, low birth weight, delayed development, mental retardation and heart and other birth defects. But until recently, no one had taken a close look at the consequences of much lower levels of alcohol consumption during pregnancy.
In the U.S., complete abstinence from alcohol during pregnancy is promoted by the surgeon general, the Centers for Disease Control and Prevention and other public health agencies. That's because no one has ever conducted (nor likely will ever conduct) a study to determine if there is a safe level of alcohol consumption during pregnancy. Scientists were, however, able to get at the issue by taking advantage of more lenient attitudes that exist in Britain, where the Department of Health recommends that if pregnant women choose to drink, they should have no more than two drinks once or twice per week to protect a baby's health.
Yvonne Kelly, an epidemiologist at University of Essex in Colchester, England, and colleagues analyzed data from more than 18,500 families with children born between September 2000 and July 2002. "We weren't setting out to say, 'Drink during pregnancy; it's good for you.' Rather, we were asking, 'Are these children really not at any increased risk [for problems] from light drinking?' " Kelly says.
The answer, she says, was very conclusively no — even after the team adjusted the stats as much as they could to rule out the influence of factors such as socioeconomic status, mother's health and age and parenting styles. Children born to mothers who drank an average of one to two drinks per week during pregnancy (or one to two drinks on a special occasion) had kids who performed just as well in cognitive and behavioral tests at age 3 and 5 as those born to women who usually drank alcohol but abstained during pregnancy.
"Children born to light drinkers don't appear to be at any increased risk for difficulties compared to women who chose not to drink in pregnancy," says Kelly of the finding, published in October in the Journal of Epidemiology and Community Health. But, she adds, "never, ever get drunk during pregnancy — it's bad for you and the child you are carrying."
Trying labor after a previous caesarean
Last year, the American College of Obstetrics and Gynecology (ACOG) revised its guidelines to doctors on vaginal birth after caesarean, or VBAC.
In the past, obstetricians had become increasingly concerned that women who had a scar across their uterus from a prior caesarean delivery and were at an increased risk of uterine rupture might suffer complications that could threaten the life of mom and baby. That perception fueled policies at hospitals, mainly dictated by liability insurance carriers that were unwilling to accept the extremely low but catastrophic risk of maternal and newborn death due to uterine rupture.
However, in 2010 the National Institutes of Health compiled the evidence from major VBAC studies, which included more than 20,000 women. It clearly showed how low the risks actually were, even for women who had had two previous caesarean deliveries.
For women with a normal pregnancy who had one previous caesarean, the risk of uterine rupture is less than 1%, the studies showed. For women with two previous caesareans, the risk is slightly higher but is still less than 2%.
The risk of maternal death (about .02%) was not increased at all compared with women who elected to have a repeat caesarean.
In its updated guidelines, changed to reflect the new data, ACOG concluded that a woman should be allowed to try for a VBAC provided she has none of the risk factors that can hinder vaginal birth and that the hospital has the capability to perform an emergency caesarean if needed. This usually means having an anesthesiologist on duty 24 hours. The new guidelines also allow a woman with two prior caesareans and a woman carrying twins to be candidates for VBACs.
"No one should be coerced into an operation they don't want," says Dr. William Grobman, maternal and fetal medicine specialist at Northwestern University in Chicago, who co-wrote the guidelines.
But, he adds, women and their providers should have early discussions to find a hospital that can safely accommodate trying for a VBAC.
On average, about 70% of women who try for a VBAC are successful, but for any individual woman and pregnancy, the chances may be much higher or lower depending on factors such as the baby's predicted weight and position at time of labor, and a mother's previous history of failed labors.
Old wives' tales and maternity go hand in hand. But often the advice isn't backed up by science.
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