Our experts weigh in on natural ways to induce labor and reveal which home remedies really work when it comes to speeding things up.

You patiently await your due date, eyeing it on your calendar and instructing loved ones to prepare for it days in advance. But when the date comes and goes with nary a contraction, you might be tempted to take matters into your own hands and research how to induce labor yourself.

"I see a lot of people who are tired of being pregnant, want it to be over and ask, 'What else can I do?' " says Jonathan Schaffir, M.D., an associate professor of obstetrics and gynecology at Ohio State University College of Medicine in Columbus.

According to a study by Dr. Schaffir and his colleagues, more than half of pregnant people turn to non-pharmacological approaches to hasten labor as they approach or go past their due dates, but fewer than half tell their doctors or midwives what they're up to. That's troubling, doctors and midwives say, because although some folk methods may work, some come with unintended consequences.

Critical fetal development continues to take place even in the final weeks of gestation. So despite the nagging backaches, sleepless nights, and countless bathroom trips, moms-to-be are advised to wait until after 39 weeks pregnant before considering any induction methods (including pharmacological) unless an induction is medically indicated.

Even then, you should know the pros and cons of each method and discuss them with your healthcare provider. Here's a look at the natural ways to induce labor at home.

Nipple Stimulation to Induce Labor

Prolonged breast stimulation prompts the pituitary gland to release contraction-inducing oxytocin, the same powerful hormone that initiates your milk let-down response and can lead to severe cramps when a newborn suckles. Its synthetic form, Pitocin, is the most common drug used to induce labor, and studies indicate that stimulating it naturally can be effective as well. A Cochrane Database review that included 719 women at 37 weeks pregnant or beyond found that nearly 40 percent of those who stimulated their nipples for one to three hours daily had their babies within three days, while only 6 percent of the control group gave birth.

But aside from the impracticalities (who has time to do this for hours on end?), this method comes with serious risks: "We know it works," says Suzy Myers, C.P.M., a certified professional midwife and chairwoman of the department of midwifery at Bastyr University in Kenmore, Washington. "But you have to be very careful that you are not overstimulating the uterus and making the contractions too strong or too close together. You also have to make sure the baby is tolerating it well by having your health care provider monitor his or her heartbeat."

Sex to Induce Labor

Although research results are mixed, anecdotes abound about late babies making an entrance soon after a love-making session. Semen contains cervix-softening fats called prostaglandins (also used in medical induction) and a woman's orgasm can lead to strong uterine contractions.

One study of 200 healthy women found that those who had sex after 36 weeks pregnant were significantly less likely to go past their due date or require labor induction. But another study published in the British Journal of Obstetrics and Gynecology found no difference between sexually active and abstinent moms when it came to length of gestation. "If a woman has a low risk for premature labor and no placenta previa, it won't hurt to try," says Dr. Schaffir.

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Castor Oil and Spicy Food

Midwives have long recommended inducing labor naturally by drinking castor oil (2 ounces in a glass of orange juice or mixed with ice cream). The idea is that castor oil can stimulate the smooth muscle of the bowels, promote the release of prostaglandin, and nudge the nearby uterus into action.

Research results are varied, but two recent trials showed that full-term pregnant people who were given castor oil were more likely to go into labor within 24 hours. But the side effects—including nausea, explosive diarrhea, and dehydration— can be grueling, Myers says.

A safer bet for those past 39 weeks? Load up on spicy food, which could have similar results without the nasty side effects (but be prepared for heartburn and puffy ankles, because spicy food taxes your digestive system).

Herbs and Acupuncture

Midwives most commonly suggest evening primrose oil and blue cohosh as natural ways to induce labor. Though each herb has a plausible mechanism for working, they also come with potential downsides.

Evening primrose oil, which is prescribed in capsule form to be taken three times a day or rubbed directly on the cervix, is believed to help soften the cervix and ready it for labor. However, the few published studies that have looked at its effectiveness failed to find that its use caused labor to begin any earlier. But one study suggests it may actually prolong the active phase of labor and boost the incidence of certain labor complications (such as arrested descent of the fetus in the birth canal).

Both blue (Caulophyllum) and black cohosh (Cimicifuga) have been used to treat menstrual ailments for centuries. However, some studies have suggested that blue cohosh can have some dangerous side effects in pregnancy, so it should be avoided.

Meanwhile, raspberry tea is often recommended in the weeks before a due date to tone the uterus but hasn't proved to have any effect on labor. And numerous studies have suggested that using acupuncture to induce labor naturally is promising, but other studies link it to prolonged pregnancy.

Exercise and Patience

Forty-three percent of the respondents in Dr. Schaffir's study said they exercised more in the final days of pregnancy in hopes of bringing on labor. But although good for you, exercise hasn't proved to speed labor, Dr. Schaffir says.

His best advice to past-due women longing for that first contraction? Skip the home remedies to induce labor, eat right, rest, and enjoy those last few days of pregnancy as much as possible. "The safest and healthiest labor is one that starts spontaneously," Dr. Schaffir says.