By the time you're 39 or 40 weeks pregnant, you may be willing to try just about anything to bring on labor more quickly, like firing up a search for "labor-inducing foods" and hitting the stores for a cart full of pineapple, eggplant and raspberry leaf tea.

But do any of the foods commonly thought to induce labor actually work? And more importantly, are they safe?

Can certain foods really induce labor?

Unfortunately, there is no miracle food that will bring on labor, at least as far as medical science is concerned. (Old wives' tales are a different story.)

So why do so many moms swear that eating a particular food kick-started their labor? Many of the foods that are reputed to bring on labor really bring on gastrointestinal distress or diarrhea, which can include cramping and uterine contractions.

If your body is ready to go into labor, the cramping and contractions caused by GI distress might get the process started faster … but with side effects ranging from the uncomfortable (hours in the bathroom) to the unsafe (dehydration).

So before trying any food, herb or supplement purported to help bring on labor, talk with your practitioner and get his or her okay first. While consuming certain things may seem like a safe, natural way to induce labor, some foods and drinks can have an unpleasant or unsafe effect.

Foods and drinks that may induce labor

Here are some of the foods and drinks commonly thought to induce labor, and what the science says about each.

Castor oil

Research has shown that castor oil can bring on contractions, but while this folk method for kick-starting labor has been used for generations, doctors are less likely to recommend it today due to its intense laxative effect, which can cause serious discomfort and dehydration.

Evening primrose oil

A recent clinical trial found that evening primrose oil was not effective in inducing labor. Still, some practitioners may recommend taking evening primrose oil to help get labor started. 

Why? Evening primrose oil contains an omega-3 fatty acid called gamma linolenic acid, or GLA, a precursor to prostaglandins. Prostaglandins, also found in sperm, are hormone-like substances that help soften the cervix in preparation for birth — one reason sex is a touted as a natural way to induce labor.

Red raspberry leaf tea

Red raspberry leaf tea has been said to boost blood flow to the uterus and thereby trigger contractions. No study has proven these claims, however, and experts say that the lack of quality data makes this tea a risky bet.

Pineapple

You may have read that eating a whole pineapple can start labor due to the enzyme bromelain, which is thought to help soften the cervix and trigger contractions. Again, this theory has yet to be supported by clinical evidence. 

Very few studies have looked at eating pineapple or drinking pineapple juice as a way to induce labor, but the little research that does exist suggests only that pineapple extract can cause contractions when applied directly to tissue samples — not when the pineapple is eaten.

Spicy foods

Spicy food can irritate your intestines, much like castor oil (albeit more gently), which may cause cramping and uterine contractions for women who are already dilated. That said, there’s no evidence to support the theory that spicy food induces labor. 

To date, only one study has found a connection between eating spicy food and going into labor — but that study focused only on preterm births. Dousing food in hot sauce still hasn’t been proven to help induce labor for a pregnant woman at 40 weeks or beyond. 

One thing spicy food is very likely to cause? Heartburn — which you’ve probably already had more than enough of during pregnancy.

Dates

In one small study, women who ate six dates per day in the month leading up to their due dates had a higher chance of going into labor on their own and had higher cervical dilation when they were admitted. A more recent study suggests that eating dates has no impact on kick-starting labor, but may help with later stages of labor. 

Dates are naturally high in fiber, and a sudden increase in the amount of fiber can cause cramping and digestive issues, so it’s possible that the effect of eating extra dates every day is similar to the effect of eating lots of spicy foods while pregnant. That said, without further study, there’s no evidence that dates are effective at inducing labor.

Eggplant

Eating eggplant to induce labor has not been studied, so there’s no medical proof that it works. 

Eggplant’s reputation as a possible labor kick-starter is most likely due to a famous eggplant parmesan dish at a restaurant near Atlanta, Georgia, called Scalini’s, known for its "eggplant babies." According to lore, when pregnant women eat the dish, they go into labor within two days. If you’d like to give it a try, the recipe is on the restaurant’s website. There’s no scientific evidence that it will work, but at least you’ll have a delicious dinner.

Balsamic vinegar

Balsamic vinegar has not been studied as a food that induces labor, so, again, there’s a lack of data to suggest whether it works. 

Balsamic seems to be another ingredient that has gotten a reputation for jump-starting labor thanks to a well-known restaurant dish — the "maternity salad" at Caioti Pizza Café in Studio City, California, which comes with a homemade balsamic vinegar dressing that some moms claim is the "secret sauce." While it sounds delicious, there’s no research to back it up.

Is it safe to eat foods that induce labor?

Talk to your practitioner before taking any herbal tonics or supplements such as castor oil, red raspberry leaf tea or evening primrose oil.

That said, most of the foods credited with kick-starting labor, such as pineapple, dates, eggplant parm and spicy dishes, are perfectly safe to eat in moderation during pregnancy, although they can sometimes lead to heartburn or an upset stomach.

Should you try inducing labor yourself with certain foods?

While the last days of pregnancy can be frustrating and uncomfortable, it’s important to play it safe and keep yourself healthy, well-rested and well-hydrated … pretty much the opposite of how you’d feel after a bout of GI distress brought on by eating a crate of pineapples.

Be gentle and patient with your body — as hard as that might sound — and talk to your practitioner about natural ways to get labor started once you’ve reached your due date.

Should you try castor oil to induce labor?

Castor oil has been shown to help start labor in some women, but its powerful laxative side effects are so unpleasant that your doctor may not recommend it.

Castor oil causes nausea, cramping, upset stomach, diarrhea and sometimes vomiting, but in multiple studies, castor oil has also been shown to induce labor within 24 hours for more than half of women at term who took a dose.

If you do get the green light to try castor oil from your health care practitioner after you’ve passed your due date, follow the dosing recommendations carefully, drink plenty of water to avoid dehydration and monitor your symptoms.

Experienced moms also suggest taking castor oil with orange juice to mask the taste, and glugging the stuff in the morning, so you’re not up all night in the bathroom.

Does pineapple induce labor?

Eating pineapple or drinking pineapple juice has not been proven to induce labor.

Pineapple (and its tropical cousin papaya) contains the enzyme bromelain, which is believed by some to soften the cervix and trigger contractions, but no research has shown that bromelain or pineapple actually have this effect. This could be because your stomach acids break down enzymes in food during digestion, or because most of the bromelain in pineapple is in the fruit’s core, not in the fleshy part that we eat.

That said, one serving of pineapple is a good source of vitamin C, folate, iron and other nutrients essential to a healthy pregnancy diet, so there’s no reason to avoid pineapple during pregnancy … but there’s also no reason to stock up on canned pineapple if you’re hoping to get labor going.

Should you drink red raspberry leaf tea to induce labor?

Red raspberry leaf tea has been used to kick-start contractions and speed up labor and postpartum recovery since the Middle Ages. However, the research on whether it actually works is limited.

While it’s reputed to strengthen and stimulate the uterine muscles, and boost blood flow to the uterus, only two studies have shown red raspberry leaf tea to have a potential positive impact on labor — and neither of them showed that it actually induced labor.

Also experts can’t say for sure that it’s safe without further study. If red raspberry leaf tea does stimulate the uterine muscles, it could potentially pose a risk of preterm labor, so it’s best to avoid drinking it before your pregnancy is considered at term.

What's more, red raspberry leaf tea is known to have a laxative and diuretic effect, so drinking it might mean some repeat trips to the bathroom. Be sure to talk it over with your health care provider before giving red raspberry leaf tea a try.

Should you take evening primrose oil to induce labor?

Evening primrose oil may soften the cervix and help the body prepare for labor, but studies have not shown it to be an effective labor inducer. Many women try evening primrose oil as an alternative to other cervical ripening agents an OB/GYN may use, such as a prostaglandin based gel or insert, but make sure to get your practitioner’s greenlight first.

The herb can be taken orally in capsule form or inserted vaginally, and side effects include may include nausea, diarrhea and upset stomach.

Foods to avoid before labor

In addition to the better-known list of foods to avoid during pregnancy, such as unpasteurized dairy, undercooked meat, raw seafood and deli meats, some foods have been linked to starting labor too early.  

Licorice root

A chemical in licorice root called glycyrrhizin has been linked to preterm births in a recent study, as well as potential long-term health risks for babies when consumed in large quantities. The study originated in Finland, where licorice root is especially popular, but the National Institutes of Health recommends against taking licorice root supplements, especially if you are pregnant.

Black or blue cohosh

Black cohosh has long been suggested as a uterine stimulant to help kick-start labor, but studies have not shown it to be effective in getting labor started. Like all herbal supplements, black cohosh should be used with caution during pregnancy. Blue cohosh, which is made from a different plant, should be avoided altogether. It has also been known to cause contractions, but its effects are more dangerous and it has been linked to serious health problems for babies and pregnant women.

When to call the doctor

It’s understandable to look for safe ways to get labor going when you’re nearing the end of your pregnancy rope. Keep your practitioner in the loop about how you’re feeling, and discuss the best ways to bring on labor based on your individual medical history and health record.

Most important of all, don’t try to induce labor before 40 weeks, and talk to your health care provider before taking herbal supplements such as castor oil, red raspberry leaf tea or evening primrose oil. If you experience low back pain, abdominal cramping or bleeding, seek medical attention immediately.

There's no proof that any foods will start labor before your body is good and ready. So you might just have to make the best of the waiting.

Plan a night out before your baby's arrival. Wear a fun outfit and go to a super fancy restaurant with your partner or a few pals. Make sure to order your favorite appetizer and main course — with an eye on the dessert cart to come. Sit down, relax and indulge in a really good meal, and take comfort in the fact that you're enjoying the calm before the storm!