Interventions for preventing postpartum constipation

Background: Postpartum constipation, with symptoms, such as pain or discomfort, straining, and hard stool, is a common condition affecting mothers. Haemorrhoids, pain at the episiotomy site, effects of pregnancy hormones, and haematinics used in pregnancy can increase the risk of postpartum constipation. Eating a high-fibre diet and increasing fluid intake are usually encouraged. Although laxatives are commonly used in relieving constipation, the effectiveness and safety of available interventions for preventing postpartum constipation should be ascertained. This is an update of a review first published in 2015.

Objectives: To evaluate the effectiveness and safety of interventions for preventing postpartum constipation.

Search methods: We searched Cochrane Pregnancy and Childbirth's Trials Register, and two trials registers ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (7 October 2019), and screened reference lists of retrieved trials.

Selection criteria: We considered all randomised controlled trials (RCTs) comparing any intervention for preventing postpartum constipation versus another intervention, placebo, or no intervention in postpartum women. Interventions could include pharmacological (e.g. laxatives) and non-pharmacological interventions (e.g. acupuncture, educational and behavioural interventions). Quasi-randomised trials and cluster-RCTs were eligible for inclusion; none were identified. Trials using a cross-over design were not eligible.

Data collection and analysis: Two review authors independently screened the results of the search to select potentially relevant trials, extracted data, assessed risk of bias, and the certainty of the evidence, using the GRADE approach. We did not pool results in a meta-analysis, but reported them per study.

Main results: We included five trials (1208 postpartum mothers); three RCTs and two quasi-RCTs. Four trials compared a laxative with placebo; one compared a laxative plus a bulking agent versus the same laxative alone, in women who underwent surgical repair of third degree perineal tears. Trials were poorly reported, and four of the five trials were published over 40 years ago. We judged the risk of bias to be unclear for most domains. Overall, we found a high risk of selection and attrition bias. Laxative versus placebo We included four trials in this comparison. Two of the trials examined the effects of laxatives that are no longer used; one has been found to have carcinogenic properties (Danthron), and the other is not recommended for lactating women (Bisoxatin acetate); therefore, we did not include their results in our main findings. None of the trials included in this comparison assessed our primary outcomes: pain or straining on defecation, incidence of postpartum constipation, or quality of life; or many of our secondary outcomes. A laxative (senna) may increase the number of women having their first bowel movement within 24 hours after delivery (risk ratio (RR) 2.90, 95% confidence interval (CI) 2.24 to 3.75; 1 trial, 471 women; low-certainty evidence); may have little or no effect on the number of women having their first bowel movement on day one after delivery (RR 0.94, 95% CI 0.72 to 1.22; 1 trial, 471 women; very low-certainty evidence); may reduce the number of women having their first bowel movement on day two (RR 0.23, 95% CI 0.11 to 0.45; 1 trial, 471 women; low-certainty evidence); and day three (RR 0.05, 95% CI 0.00 to 0.89; 1 trial, 471 women; low-certainty evidence); and may have little or no effect on the number of women having their first bowel movement on day four after delivery (RR 0.22, 95% CI 0.03 to 1.87; 1 trial, 471 women; very low-certainty evidence), but some of the evidence is very uncertain. Adverse effects were poorly reported. Low-certainty evidence suggests that the laxative (senna) may increase the number of women experiencing abdominal cramps (RR 4.23, 95% CI 1.75 to 10.19; 1 trial, 471 women). Very low-certainty evidence suggests that laxatives taken by the mother may have little or no effect on loose stools in the baby (RR 0.62, 95% CI 0.16 to 2.41; 1 trial, 281 babies); or diarrhoea (RR 2.46, 95% CI 0.23 to 26.82; 1 trial, 281 babies). Laxative plus bulking agent versus laxative only Very low-certainty evidence from one trial (147 women) suggests no evidence of a difference between these two groups of women who underwent surgical repair of third degree perineal tears; only median and range data were reported. The trial also reported no evidence of a difference in the incidence of postpartum constipation (data not reported), but did not report on quality of life. Time to first bowel movement was reported as a median (range); very low-certainty evidence suggests little or no difference between the two groups. A laxative plus bulking agent may increase the number of women having any episode of faecal incontinence during the first 10 days postpartum (RR 1.81, 95% CI 1.01 to 3.23; 1 trial, 147 women; very low-certainty evidence). The trial did not report on adverse effects of the intervention on babies, or many of our secondary outcomes.

Authors' conclusions: There is insufficient evidence to make general conclusions about the effectiveness and safety of laxatives for preventing postpartum constipation. The evidence in this review was assessed as low to very low-certainty evidence, with downgrading decisions based on limitations in study design, indirectness and imprecision. We did not identify any trials assessing educational or behavioural interventions. We identified four trials that examined laxatives versus placebo, and one that examined laxatives versus laxatives plus stool bulking agents. Further, rigorous trials are needed to assess the effectiveness and safety of laxatives during the postpartum period for preventing constipation. Trials should assess educational and behavioural interventions, and positions that enhance defecation. They should report on the primary outcomes from this review: pain or straining on defecation, incidence of postpartum constipation, quality of life, time to first bowel movement after delivery, and adverse effects caused by the intervention, such as: nausea or vomiting, pain, and flatus.