Vaginal misoprostol is FDA approved only for reducing the risk of NSAID-induced gastric ulcers; its use for cervical ripening and labor induction is off label. Vaginal absorption peaks later and lasts longer than oral absorption, and a tablet cannot be retrieved once absorbed. Tachysystole shortens the rest between contractions, and fetal oxygen saturation falls as contraction frequency rises. Doses above 25 mcg every 4 hours caused more uterine hyperstimulation. Every woman offered misoprostol should give informed consent that covers its off-label status, the boxed warning, the risks, and the alternatives.
Scene-by-scene transcript
0 to 2 s. Title: Vaginal misoprostol. When contractions outrun fetal oxygen.
2 to 6 s. What misoprostol is: a synthetic prostaglandin E1 analog, supplied as 100 mcg and 200 mcg oral tablets. FDA-approved indication: reducing the risk of NSAID-induced gastric ulcers in patients at high risk. Labeled dose for that use: 200 mcg by mouth four times daily with food.
6 to 10 s. How and why it is used to induce labor: off label, about 25 mcg (one quarter of a 100 mcg tablet) placed in the vagina every 4 to 6 hours. It ripens the cervix and induces contractions. In more than 45 trials with over 5,400 women, vaginal misoprostol achieved vaginal delivery within 24 hours more often than oxytocin or vaginal PGE2.
10 to 14 s. The vaginal route peaks later and stays longer: time to peak 80 vs 34 minutes; exposure over 6 hours 957 vs 300 pg·h/mL (400 mcg in 20 women, not a labor dose). Absorption varied widely between women.
14 to 18 s. Normal activity, 3 contractions in 10 minutes: oxygen dips with each contraction and recovers during the rest (schematic).
18 to 22 s. Tachysystole, more than 5 contractions in 10 minutes averaged over 30 minutes: the rest is too short to recover, and oxygen ratchets down (schematic).
22 to 26 s. Measured fetal oxygen saturation fell from 52.1% to 41.5% (minus 20%) with 5 to fewer than 6 contractions per 10 minutes, and from 52.0% to 36.7% (minus 29%) with 6 or more. Oxytocin-induced hyperstimulation, 56 women.
26 to 28 s. You can stop an infusion. You cannot retrieve an absorbed tablet.
28 to 32 s. The original boxed warning, before May 2002, as summarized in the literature: contraindicated in pregnancy because of its abortifacient properties. In May 2002 this was narrowed to ulcer prevention in pregnant women. The current boxed warning still states that use in pregnant women can cause birth defects, abortion, premature birth or uterine rupture.
32 to 36 s. Not FDA approved for cervical ripening or labor induction. The label calls these uses outside of its approved indication; its boxed warning reports uterine rupture when given to induce labor.
36 to 40 s. Informed consent before the first dose. Every woman offered misoprostol should be told: it is used off label; it can cause tachysystole and lower fetal oxygen; uterine rupture risk rises with prior uterine surgery, including cesarean; once absorbed it cannot be stopped or removed; the alternatives, and her right to decline.
40 to 46 s. Take-home: doses above 25 mcg every 4 hours caused more hyperstimulation. More uterine activity was associated with umbilical artery pH 7.11 or less. Count contractions and protect the rest interval. Informed consent before the first dose, because it is off label, carries a boxed warning in pregnancy, cannot be stopped once absorbed, and alternatives exist. The decision is hers.
Publications used in this film
Simpson KR, James DC. Effects of oxytocin-induced uterine hyperstimulation during labor on fetal oxygen status and fetal heart rate patterns. Am J Obstet Gynecol. 2008;199(1):34.e1-5. doi:10.1016/j.ajog.2007.12.015 Observational, retrospectiveFetal SpO2 fell 20% and 29% with hyperstimulation (56 women). Oxytocin, not misoprostol: used for the physiology of tachysystole.
Zieman M, Fong SK, Benowitz NL, Banskter D, Darney PD. Absorption kinetics of misoprostol with oral or vaginal administration. Obstet Gynecol. 1997;90(1):88-92. doi:10.1016/S0029-7844(97)00111-7 Pharmacokinetic studyVaginal peak 80 vs 34 min oral; larger 6-hour exposure. 400 mcg in 20 women, not a labor dose.
Hofmeyr GJ, Gülmezoglu AM, Pileggi C. Vaginal misoprostol for cervical ripening and induction of labour. Cochrane Database Syst Rev. 2010;(10):CD000941. doi:10.1002/14651858.CD000941.pub2 Systematic review, 121 trialsDoses above 25 mcg every 4 hours: more uterine hyperstimulation.
Macones GA, Hankins GD, Spong CY, Hauth J, Moore T. The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines. Obstet Gynecol. 2008;112(3):661-6. doi:10.1097/AOG.0b013e3181841395 Consensus definitionTachysystole: more than 5 contractions in 10 minutes, averaged over 30 minutes.
Bakker PC, Kurver PH, Kuik DJ, Van Geijn HP. Elevated uterine activity increases the risk of fetal acidosis at birth. Am J Obstet Gynecol. 2007;196(4):313.e1-6. doi:10.1016/j.ajog.2006.11.035 Observational, 1,433 IUP recordingsMore uterine activity associated with umbilical artery pH 7.11 or less.
US Food and Drug Administration. Cytotec (misoprostol) tablets: prescribing information [Internet]. New York: Pfizer; revised 2018 Feb [cited 2026 Sep 28]. Available from: https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/019268s051lbl.pdf Regulatory labelApproved indication is NSAID-induced gastric ulcer risk reduction; ripening and induction are outside it. Boxed warning on uterine rupture.
Goldberg AB, Wing DA. Induction of labor: the misoprostol controversy. J Midwifery Womens Health. 2003;48(4):244-8. doi:10.1016/s1526-9523(03)00087-4 ReviewLabeling history: the pre-2002 label warned that misoprostol was contraindicated in pregnancy; in May 2002 this was narrowed to use as an antiulcer drug in pregnant women.
Version 1.0. Published 28 September 2026. Last reviewed 28 September 2026. Traces labeled schematic are teaching illustrations; all other numbers come from the publications listed.