Constipation

Constipation is a common gastrointestinal symptom in pregnancy, particularly in the first trimester. Guidance about increasing dietary fibre and appropriate use of laxatives may assist women to treat constipation and reduce the risk of further episodes.

55.1 Background

Constipation is the delay in the passage of food residue, associated with painful defecation and abdominal discomfort. Rising levels of progesterone in pregnancy can cause a reduction in gastric motility and increased gastric transit time. Poor dietary fibre intake can contribute to women experiencing constipation during pregnancy, as at any time of life. Iron supplementation, common during pregnancy, is also associated with constipation (Bradley et al 2007). In Aboriginal and Torres Strait Islander communities with a high prevalence of anaemia, iron supplementation is common.

Constipation is generally defined by Rome II criteria: the presence of at least two of the following symptoms for at least one in four defecations: straining, lumpy or hard stools, sensation of incomplete evacuation, sensation of anorectal obstruction, manual manoeuvres to facilitate defecation, and fewer than three defecations per week.

55.1.1 Prevalence of constipation in pregnancy

Constipation is a commonly reported condition during pregnancy that appears to decrease as the pregnancy progresses.

• A case series study (Meyer et al 1994) found that 39% of pregnant women reported symptoms of constipation at 14 weeks, 30% at 28 weeks and 20% at 36 weeks; this study may have resulted in overestimates, as routine iron supplementation was recommended for all pregnant women in the United Kingdom at the time the study was conducted.
• Later studies have found that constipation affects up to 25% of women during pregnancy:
  • a prospective case series study (Bradley et al 2007) found prevalence rates of 24% (95% CI 16–33%), 26% (95% CI 17–38%), 16% (95% CI 8–26%) in the first, second, and third trimesters, respectively. In multivariable longitudinal analysis, iron supplements (OR 3.5; 95% CI 1.04–12.10) and past constipation treatment (OR 3.58; 95% CI 1.50–8.57) were associated with constipation during pregnancy
  • a correlational study (Ponce et al 2008) found prevalence rates of 29.6%, 19% and 21.8% in the first, second and third trimesters respectively. This study also reported laxative use among pregnant women as 11% (95% CI 7–16), 15% (95% CI 10–21) and 13.5% (95% CI 8–19) in the first, second and third trimesters.

55.2 Guidance on managing constipation

The first-line treatment for constipation is increasing dietary fibre and fluid intake. Dietary fibre intake can be improved by eating more wholegrain foods, fruit and vegetables, or through wheat or bran fibre supplementation. Where fibre supplementation does not alleviate symptoms, laxatives (stimulant, bulk-forming or osmotic) may be helpful in the short-term, although they can cause adverse side effects such as abdominal pain and diarrhoea.

55.2.1 Effectiveness of treatments

Findings are consistent across the NICE guidelines and the systematic review conducted to inform these Guidelines.

• Increasing fluid intake: While there are no RCTs or cohort studies in this area, there is some evidence to suggest that dietary factors such as water intake may play a role in preventing, or alleviating, bowel habit perturbations during and after pregnancy (Derbyshire et al 2006). In spite of the lack of high-level evidence, increased fluid intake should be recommended as one of the first measures to relieve constipation in pregnancy. Increasing fluid intake is not expensive, is readily available and has several other beneficial effects during pregnancy (Vasquez 2008).
• Dietary fibre supplementation: Evidence from a Cochrane review (Jewell & Young 2009) based on two RCTs (n = 215) supports the effectiveness of fibre supplementation in safely treating constipation in pregnancy. Fibre supplements were found to increase the frequency of defecation (OR: 0.18; 95% CI 0.05–0.67), lead to softer stools and appear to have no adverse effects.
• Laxatives: The same Cochrane review (Jewell & Young 2009) found that when discomfort was not alleviated by fibre supplementation, stimulant laxatives were more effective than bulk-forming laxatives (Peto OR 0.30; 95% CI 0.14–0.61), although stimulants were associated with significantly more abdominal pain and diarrhoea. Preliminary evidence indicates that osmotic laxatives (eg polyethylene glycol or PEG) are effective and well tolerated during pregnancy (Neri et al 2004) but currently there is insufficient evidence about potential effects on the fetus (Vasquez 2008).

55.3 Practice summary: constipation

When

At the first contact with all women and at subsequent contacts for women who report symptoms of constipation.

Who

• Midwife
• maternal and child health nurse
• GP; obstetrician
• Aboriginal and Torres Strait Islander health worker
• multicultural health worker
• practice nurse
• allied health professional
• pharmacist.

What

• Advise about fluid intake
  Drinking more fluids has a range of benefits and may assist in easing constipation. Water is a good source of fluids as it hydrates without adding additional energy to the diet. Other drinks such as milks and fruit juices add variety and nutrients. Intake of fluids containing added sugars should be moderated.
• Talk about dietary fibre
  Advise all women to eat a wide variety of nutritious foods, including plenty of vegetables, fruit, wholegrain cereals and breads, nuts, seeds and legumes. Bran or wheat fibre supplementation is safe and effective during pregnancy and may relieve symptoms. Fibre supplements should be introduced slowly and plenty of water consumed while they are being taken.
• Discuss laxative use
  Laxatives can be used to relieve symptoms but should not be used long-term. Bulk-forming laxatives may cause fewer side effects than stimulant laxatives.

55.4 Resources

• NHMRC (2013) Australian Dietary Guidelines. Canberra: Commonwealth of Australia.