Interventions for treating constipation in pregnancy

What is the issue?

The term 'constipation' is defined as difficulty in passing stool and reduced frequency of bowel movements. It is characterised by discomfort, excessive straining, hard or lumpy stools, a sensation of incomplete evacuation, and infrequent bowel movements. Constipation is a common symptom experienced during pregnancy. This can result from a combination of factors, including changes in hormones during pregnancy affecting the digestive system, reduced physical activity and changes in dietary habits during pregnancy. In addition, as the baby grows it can press on the mother's intestines and cause digestive delays/obstructions.

Why is this important?

Constipation during pregnancy is associated with impaired quality of life and distress for pregnant women as well as physical problems including, occasionally, haemorrhoids. There are a range of suggested treatments with drugs, supplements or dietary modifications.

Generally, non-pharmacological interventions (changes in diet, water intake and exercise) are recommended initially, followed by pharmacological interventions if the non-pharmacological interventions fail or are insufficient. Pharmacological interventions include medications from a wide range of drug classes including lubricants, bulk-forming agents, osmotic laxatives, stimulant laxatives, stool softeners, and enemas and suppositories.

This review looked at the benefits of drug and non-drug interventions for constipation in pregnancy and whether they are safe for women and babies.

What evidence did we find?

We identified four studies, but only two studies (with a total of 180 women) provided data for analysis.The studies looked at stimulant laxatives compared with bulk-forming laxatives and dietary fibre supplementation versus no intervention. The included studies were judged to be of moderate quality.

We looked at two main comparisons. In the first, we found that stimulant laxatives may be more effective in improving constipation than bulk-forming laxatives (moderate quality evidence) but may also cause more abdominal discomfort (low quality evidence) and diarrhoea (moderate quality evidence) and we found no difference in women's satisfaction (moderate quality evidence). However, when we removed data relating to an intervention called Normax (dioctyl sodium sulphosuccinate and dihydroxy anthraquinone), which is no longer routinely used in pregnancy, there was no longer a clear difference between stimulant and bulk-forming laxatives in terms of abdominal discomfort and diarrhoea.

The second comparison, between fibre supplementation and no intervention, found that fibre supplementation may be effective in increasing the frequency of stools (moderate quality evidence). Fibre supplementation was associated with improved stool consistency as defined by trialists (hard stool decreased by 11% to 14%, normal stool increased by 5% to 10%, and loose stool increased by 0% to 6%).

There were no studies that looked at others types of interventions like osmotic laxatives, stool softeners, lubricant laxatives and enemas and suppositories.

What does this mean?

What little evidence there is, suggests that dietary fibre supplementation may increase the frequency of stools. If choosing between stimulant and bulk-forming laxatives, then stimulant may relieve constipation better but may cause more abdominal discomfort and diarrhoea.

More research in this area is needed.

Authors' conclusions: 

There is insufficient evidence to comprehensively assess the effectiveness and safety of interventions (pharmacological and non-pharmacological) for treating constipation in pregnancy, due to limited data (few studies with small sample size and no meta-analyses). Compared with bulk-forming laxatives, stimulant laxatives appear to be more effective in improvement of constipation (moderate quality evidence), but are accompanied by an increase in diarrhoea (moderate quality evidence) and abdominal discomfort (low quality evidence) and no difference in women's satisfaction (moderate quality evidence). Additionally, fibre supplementation may increase frequency of stools compared with no intervention (moderate quality evidence), although these results were of moderate risk of bias.

There were no data for a comparison of other types of interventions, such as osmotic laxatives, stool softeners, lubricant laxatives and enemas and suppositories.

More RCTs evaluating interventions for treating constipation in pregnancy are needed. These should cover different settings and evaluate the effectiveness of various interventions (including fibre, osmotic, and stimulant laxatives) on improvement in constipation, pain on defecation, frequency of stools and consistency of stools.

Read the full abstract...
Background: 

Constipation is a common symptom experienced during pregnancy. It has a range of consequences from reduced quality of life and perception of physical health to haemorrhoids. An understanding of the effectiveness and safety of treatments for constipation in pregnancy is important for the clinician managing pregnant women.

Objectives: 

To assess the effectiveness and safety of interventions (pharmacological and non-pharmacological) for treating constipation in pregnancy.

Search strategy: 

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 April 2015), ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) (30 April 2015) and reference lists of retrieved studies.

Selection criteria: 

We considered all published, unpublished and ongoing randomised controlled trials (RCTs), cluster-RCTs and quasi-RCTs, evaluating interventions (pharmacological and non-pharmacological) for constipation in pregnancy. Cross-over studies were not eligible for inclusion in this review. Trials published in abstract form only (without full text publication) were not eligible for inclusion.

We compared one intervention (pharmacological or non-pharmacological) against another intervention, placebo or no treatment.

Data collection and analysis: 

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy.

Main results: 

Four studies were included, but only two studies with a total of 180 women contributed data to this review. It was not clear whether they were RCTs or quasi-RCTs because the sequence generation was unclear. We classified the overall risk of bias of three studies as moderate and one study as high risk of bias. No meta-analyses were carried out due to insufficient data.

There were no cluster-RCTs identified for inclusion. Comparisons were available for stimulant laxatives versus bulk-forming laxatives, and fibre supplementation versus no intervention. There were no data available for any other comparisons.

During the review process we found that studies reported changes in symptoms in different ways. To capture all data available, we added a new primary outcome (improvement in constipation) - this new outcome was not prespecified in our published protocol.

Stimulant laxatives versus bulk-forming laxatives

No data were identified for any of this review's prespecified primary outcomes: pain on defecation, frequency of stools and consistency of stools.

Compared to bulk-forming laxatives, pregnant women who received stimulant laxatives (Senokot or Normax) had an improvement in constipation (risk ratio (RR) 1.59, 95% confidence interval (CI) 1.21 to 2.09; 140 women, one study, moderate quality of evidence), but also had more abdominal discomfort (RR 2.33, 95% CI 1.15 to 4.73; 140 women, one study, low quality of evidence), and a borderline difference in diarrhoea (RR 4.50, 95% CI 1.01 to 20.09; 140 women, one study, moderate quality of evidence). In addition, there was no clear difference in women's satisfaction (RR 1.06, 95% CI 0.77 to 1.46; 140 women, one study, moderate quality of evidence).

One of the stimulant laxatives, Normax (dioctyl sodium sulphosuccinate and dihydroxy anthraquinone) is no longer used for the treatment of constipation in pregnant women (and the package information advises that it should not be used during pregnancy or breastfeeding). We therefore carried out a non-prespecified sensitivity analysis with the data for Senokot and Normax presented separately. Results for Senokot and Normax were very similar, thus results for the individual drugs largely reflected findings for the combined analysis, although when individual drugs were compared with bulk-forming laxatives there was no longer a clear difference between groups in terms of abdominal discomfort and diarrhoea.

No usable data were identified for any of this review's secondary outcomes: quality of life; dehydration; electrolyte imbalance; acute allergic reaction; or asthma.

Fibre supplementation versus no intervention

Pregnant women who received fibre supplementation had a higher frequency of stools compared to no intervention (mean difference (MD) 2.24 times per week, 95% CI 0.96 to 3.52; 40 women, one study, moderate quality of evidence). Fibre supplementation was associated with improved stool consistency as defined by trialists (hard stool decreased by 11% to 14%, normal stool increased by 5% to 10%, and loose stool increased by 0% to 6%).

No usable data were reported for either the primary outcomes of pain on defecation and improvement in constipation or any of this review's secondary outcomes as listed above.

Quality

Five outcomes were assessed with the GRADE software: improvement in constipation, frequency of stools, abdominal discomfort, diarrhoea and women's satisfaction. These were assessed to be of moderate quality except for abdominal discomfort which was assessed to be of low quality. The results should therefore be interpreted with caution. There were no data available for evaluation of pain on defecation or consistency of stools.

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