Hurry Up, Baby! The Truth about What Induces Labor

Can a change in weather induce labor? What about a spicy meal, or castor oil? I’m sure anyone who has been pregnant in the third trimester has looked into natural ways to get labor started.

Myths & Facts Around Inducing Labor

But are there old wives’ tales and special recipes that actually work? Research on this topic is far from conclusive. Women report success with a wide variety of behaviors and substances for getting labor going. One study¹ surveyed over 600 women who had experienced spontaneous labor. Of those who reported a specific labor trigger:

• 32% reported physical activity (usually walking)
• 24% of clinician-mediated trigger (like stripping membranes)
• 19% a natural phenomenon
• 14% some other physical trigger (including sexual activity)
• 12% reported ingesting something (foods or substances)
• 12% reported an emotional trigger
• 7% reported maternal illness

With the exceptions of walking and sexual intercourse, few women reported any one specific trigger.

It is important to consider the efficacy and potential safety of various interventions to get labor started, keeping the safety of mother and baby paramount. Trying to induce labor prior to term, or 37 weeks gestation, poses risks to baby, as preterm birth is associated with NICU admissions and neonatal morbidity.

Common Labor Induction Approaches

Here is what we know about the more common approaches suggested for inducing labor.

Weather

If you ask those who work on any labor and delivery unit if storms lead to labor, they would say yes. Low barometric pressure associated with storms has been shown in some studies to induce rupture of membranes and delivery,²  however many other studies have been less conclusive.

Although heat exhaustion and heat stroke are more likely in pregnant women, and high heat can be teratogenic (disruptive to normal growth and development) for babies very early in pregnancy, heat has not been established as a trigger for labor.

Nipple Stimulation

Nipple stimulation prompts the release of oxytocin, which is a naturally occurring hormone that induces uterine contractions in addition to contracting ducts in the breast tissue, leading to let down during breast feeding. Although this is a natural and inexpensive method for inducing labor, studies have shown it is not particularly effective, particularly when compared with Pitocin (a synthetic form of oxytocin).³

Sexual Intercourse

Semen contains prostaglandins, which are also used in labor and delivery to soften and open the cervix, and can cause contractions. Studies on the ability of this activity to start labor are mixed, but it will likely cause contractions. One must also be cautious if your doctor has recommended pelvic rest during pregnancy for various conditions.

Acupuncture

While some believe this will improve cervical readiness for labor and it appears to be safe, research has not determined whether it works.

Walking

Regular walks are a healthy way to stay active throughout pregnancy. Some studies suggest that in later pregnancy, they can increase spontaneous onset of labor and decrease induction, cesarean and instrumental delivery, however further investigation is needed.⁴

Castor or Cod Liver Oil

There is no scientific evidence these laxatives lead to contractions, and they can cause stomach upset and diarrhea.

Foods and Drinks

I’m sure you have heard of many things to eat or drink that could help get labor going. Unfortunately, nothing has been established to help in various studies on a variety of foods and drinks. Generally, however, it would not be harmful to try. If you plan on eating or drinking something to help induce labor, it is important not to do so until you are term to avoid the risks to the baby of delivering prematurely.

• Spicy food can upset the stomach, which can lead to uterine irritation and contractions. They can also cause heartburn and possible stomach upset – and not help trigger labor.
• Pineapple has an enzyme called bromelain which can soften the cervix, but the natural acid in your stomach does not allow the enzyme to be active after you consume it. Pineapple can also cause heartburn and acid reflux.
• Black cohosh is a supplement that some women use for menopausal symptoms and is thought to make the uterus contract. It’s utility in this regard is not well established in research studies,⁵ and there have been some reports of complications in labor and delivery when used at the end of pregnancy.⁶
• Raspberry leaf tea lacks quality evidence to establish it induces labor, but is likely safe to take in pregnancy.⁷

Membrane Stripping

Membrane stripping, or sweeping, is a technique where a clinician inserts one or two fingers into the cervix and, with a circular sweeping motion, attempts to detach the inferior area of the membranes from the lower uterine segment. This mechanism facilitates the release of hormones and prostaglandins that encourage cervical effacement and dilation, promoting spontaneous labor.

A Cochrane Review of membrane sweeping concluded that this intervention may be effective in achieving spontaneous onset of labor, and reduces the incidence of induction of labor when compared with expectant management. This practice is considered safe to attempt after term, when the cervix is at least a centimeter dilated, and does not increase risks to mom and baby.⁸

As uncomfortable as later stages of pregnancy can be, I encourage women to be patient and not rush labor. Many activities and practices may help and are not a threat to the pregnancy, but I would recommend not attempting to induce labor prior to 37 weeks, when the baby is full term. If you are considering trying to naturally induce labor in a new or novel way, talk to your health care provider first. We can help you understand how it may or may not work physiologically, and more importantly, ensure you and baby stay safe.

Resources:

¹ Bovbjerg ML, Evenson KR, Bradley C, Thorp JM. What started your labor? Responses from mothers in the third pregnancy, infection, and nutrition study. J Perinat Educ. 2014 Summer;23(3):155-64. doi: 10.1891/1058-1243.23.3.155. PMID: 25364220; PMCID: PMC4210668.

²Akutagawa O, Nishi H, Isaka K. Spontaneous delivery is related to barometric pressure. Arch Gynecol Obstet. 2007 Apr;275(4):249-54. doi: 10.1007/s00404-006-0259-3. Epub 2006 Sep 27. PMID: 17004080.

³ Stark EL, Athens ZG, Son M. Intrapartum nipple stimulation therapy for labor induction: a randomized controlled external pilot study of acceptability and feasibility. Am J Obstet Gynecol MFM. 2022 Mar;4(2):100575. doi: 10.1016/j.ajogmf.2022.100575. Epub 2022 Jan 15. PMID: 35042047.

⁴ Shojaei B, Loripoor M, Sheikhfathollahi M, Aminzadeh F. The effect of walking during late pregnancy on the outcomes of labor and delivery: A randomized clinical trial. J Educ Health Promot. 2021 Jul 30;10:277. doi: 10.4103/jehp.jehp_1437_20. PMID: 34485574; PMCID: PMC8395880.

⁵ Dugoua JJ, Seely D, Perri D, Koren G, Mills E. Safety and efficacy of black cohosh (Cimicifuga racemosa) during pregnancy and lactation. Can J Clin Pharmacol. 2006 Fall;13(3):e257-61. Epub 2006 Nov 3. PMID: 17085773.

⁶Blitz MJ, Smith-Levitin M, Rochelson B. Severe Hyponatremia Associated with Use of Black Cohosh during Prolonged Labor and Unsuccessful Home Birth. AJP Rep. 2016 Mar;6(1):e121-4. doi: 10.1055/s-0036-1579537. PMID: 26989565; PMCID: PMC4794442.

⁷ Bowman R, Taylor J, Muggleton S, Davis D. Biophysical effects, safety and efficacy of raspberry leaf use in pregnancy: a systematic integrative review. BMC Complement Med Ther. 2021 Feb 9;21(1):56. doi: 10.1186/s12906-021-03230-4. PMID: 33563275; PMCID: PMC7871383.

⁸ Finucane EM, Murphy DJ, Biesty LM, Gyte GM, Cotter AM, Ryan EM, Boulvain M, Devane D. Membrane sweeping for induction of labour. Cochrane Database Syst Rev. 2020 Feb 27;2(2):CD000451. doi: 10.1002/14651858.CD000451.pub3. PMID: 32103497; PMCID: PMC7044809.