As if you needed yet another reason why induction of labor and cesarean birth should be avoided unless absolutely necessary, a recent study in the United Kingdom offers yet another.
Amniotic fluid embolism (AFE), a very rare but often deadly complication of childbirth, was found to be associated with inductions and cesarean births. How AFE happens is not well understood. It is thought that amniotic fluid, fetal cells, hair, or other debris enter the mother’s bloodstream, causing cardiac and respiratory collapse. The National Amniotic Fluid Embolus Registry suggests that AFE is more like an anaphylactic reaction (allergic reaction) than an embolism, and the term anaphylactoid syndrome of pregnancy has been suggested. Incidence of AFE is estimated at one case per 8,000 – 30,000 pregnancies, but the true incidence is not known because of the difficulty of diagnosing AFE and the lack of accurate reporting of maternal deaths.¹ When AFE occurs, it is fatal approximately 80% of the time, with 50% of women dying with in the first hour of onset of symptoms. Most women who survive have permanent neurologic impairment. 5-10% of maternal mortality in the United States is attributed to AFE.²
Dr. Marian Knight was the principal investigator of the UK study. She stated, “Induction of labor was associated with a population-attributable risk of 35% in our study, suggesting that, assuming causality, if induction of labor were no longer performed, 35% of cases of amniotic fluid embolism could be prevented.“³
Dr. Knight goes on to reassure us that since inductions will continue to happen, we need to remember that AFE is very rare.
92% of the cases of AFE studied occurred in women whose membranes had ruptured at or before onset of symptoms. I find this interesting, because artificial rupture of membranes (AROM) is known to be associated with an increased risk of AFE. This is an area that needs further study.
Dr. Knight further commented, “Occurrence of amniotic fluid embolism does appear to be associated with induction of labor and caesarean delivery and it is important therefore that both risks and benefits of labor induction and cesarean delivery are considered by clinicians on an individual basis for all women.”³
Common sense tip for today: Let labor start on its own. Let the water break on its own. Let the baby be born vaginally unless it is clearly safer to birth by cesarean.
1. Clark SL, Hankins GD, Dudley DA, et al. Amniotic fluid embolism: analysis of the national registry. Am J Obstet Gynecol. Apr 1995;172(4 Pt 1):1158-67; discussion 1167-9.
2. O’Shea A, Eappen S. Amniotic fluid embolism. Int Anesthesiol Clin. 2007;45(1):17-28.
3. Lie D. Labor induction increases risk of rare amniotic fluid emboli. Medscape. Retrieved 6/8/10 from: http://cme.medscape.com/viewarticle/721414