Constipation is a common problem in pregnant women with the prevalence ranging from 11-38%. (1) The causes of constipation in pregnancy are numerous: anxiety, lack of exercise, and lack of fiber in the diet. Identifying the cause and correcting the problem is essential for preventing reoccurrence.
Non-pharmacological treatment consists of increasing dietary fiber, fiber supplementation, and a regular exercise regimen. This may be all that is necessary. If non-pharmacological methods fail to resolve symptoms of constipations, the use of laxatives is advisable. There are a wide variety of laxatives currently available. Which laxative is most suited for use in pregnancy?
PEG-based osmotic laxatives (i.e. Miralax, GoLYTELY) are ideal in pregnancy and proven to be safe and efficacious in animal studies. Systemic absorption is minimal (1-4%), and the drug is concentrated in the gastrointestinal tract. There have been no well-controlled human studies done; however animal studies report no teratogenic risk. Once daily dosing is used for PEG-based osmotic laxatives, which is convenient. Long-term use is acceptable, however in pregnancy it is advisable to discontinue medicating after resolution of symptoms. The disadvantage is that some patients complain of a salty taste. (2)
Bulk-forming laxatives (i.e. Metamucil) have a slower onset of action, but they are still effective for treatment of constipation. The disadvantage is that there is less safety data available, risk of mechanical obstruction, and complicated dose escalation schedule. (2)
Short-term use of magnesium containing osmotic laxatives (i.e lactulose, lactitol, sorbitol) is another alternative. Finally, persistent constipation can be treated with a stimulant laxative (i.e senna) (3) Stimulant laxatives should not be used long-term, only acutely.
Iron supplementation is common cause of constipation in pregnant women. Anemic pregnant women in particular suffer from these effects. Increased doses of iron are correlated with increased rates of constipation. (4)
References:
1. Jewell DJ, Young G, Interventions for treating constipation in pregnancy. Cochrane Database Syst Rev 2002
2. Tytgat, G. N., R. C. Heading, et al. (2003). "Contemporary understanding and management of reflux and constipation in the general population and pregnancy: a consensus meeting." Aliment Pharmacol Ther 18(3): 291-301.
3. Prather CM. Pregnancy-related constipation. Curr Gastroenterol Rep. Oct 2004;6(5):402-404.
4. Souza, A. I., M. Batista Filho, et al. (2009). "Adherence and side effects of three ferrous sulfate treatment regimens on anemic pregnant women in clinical trials." Cad Saude Publica 25(6): 1225-1233.
