Bulk-forming fiber supplements and stool softeners are the safest laxatives during pregnancy. Both are poorly absorbed into the bloodstream, making them unlikely to affect your baby. Osmotic laxatives are a reasonable next step if gentler options don’t work, though they’re best used short-term. Constipation affects up to half of all pregnant women, so this is one of the most common complaints in prenatal care.
Why Pregnancy Causes Constipation
Rising progesterone levels slow the movement of food through your digestive tract. This hormone relaxes smooth muscle throughout your body, including the muscles that push waste along your intestines. The result is slower transit time, which means your colon absorbs more water from stool before it reaches the rectum. Add to that a growing uterus pressing on your bowels, iron in prenatal vitamins, and the general tendency to drink less water when you’re nauseated, and constipation becomes almost predictable.
It can start as early as the first trimester and often worsens in the third, when the baby takes up the most space. The good news: several over-the-counter options have solid safety profiles for pregnancy.
Bulk-Forming Fiber Supplements
Fiber supplements are the first thing to try. Products like psyllium husk (sold as Metamucil or Konsyl) and polycarbophil (FiberCon) work by absorbing water in the intestine, which makes stool softer and bulkier so it’s easier to pass. The Mayo Clinic notes these are typically considered safe during pregnancy because they aren’t absorbed by the body. They pass through your digestive tract without entering your bloodstream, so they don’t reach the baby.
Give them a few days to work. Fiber supplements aren’t instant relief. They need consistent daily use along with plenty of water to be effective. Without adequate fluids, extra fiber can actually make constipation worse. Start with a smaller dose and increase gradually to minimize gas and bloating, which are the most common side effects. Methylcellulose (Citrucel) tends to produce less gas than psyllium if bloating is a problem for you.
Stool Softeners
Docusate sodium (Colace) is one of the most commonly recommended options during pregnancy. It works by drawing water into stool to soften it rather than stimulating the intestines to contract. Very little docusate sodium enters the bloodstream, which makes it unlikely to reach the developing baby. According to the Organization of Teratology Information Specialists, when used as directed, docusate sodium is unlikely to increase the chance of birth defects, preterm delivery, or low birth weight.
Stool softeners are gentler than true laxatives. They won’t produce a sudden urge to go. Instead, they make your next bowel movement easier to pass. Most people notice a difference within one to three days. They’re a good option if you’re dealing with hard, dry stools rather than infrequent bowel movements, and they’re often recommended alongside iron supplements, which are notorious for causing constipation.
Osmotic Laxatives: A Short-Term Option
If fiber and stool softeners aren’t enough, osmotic laxatives are the next tier. These include polyethylene glycol 3350 (MiraLAX) and lactulose. They work by pulling water into the intestine, which softens stool and stimulates movement. They’re generally considered safe for occasional use in pregnancy, but the recommendation is to keep use short-term to avoid dehydration or electrolyte imbalances.
Magnesium-based options like milk of magnesia also fall into this category. Magnesium citrate has been used in pregnancy research trials at moderate doses without significant gastrointestinal side effects compared to placebo groups. However, any magnesium-based laxative should be used occasionally rather than daily, and it’s worth running it by your provider first, especially if you have kidney issues or are already taking a magnesium supplement.
Stimulant Laxatives: Use With Caution
Stimulant laxatives like senna (Senokot) and bisacodyl (Dulcolax) work by triggering contractions in the intestinal wall. They’re effective but come with more side effects, most notably abdominal cramps. These are not first-line choices during pregnancy. They’re reserved for situations where gentler options have failed, and even then, they should be used only occasionally.
Prolonged use of stimulant laxatives can theoretically lead to electrolyte imbalances and a condition sometimes called “cathartic colon,” where the bowel becomes dependent on stimulation to function normally. For most pregnant women, a short course of a stimulant laxative under medical guidance is fine when nothing else is working, but regular use isn’t recommended.
Laxatives to Avoid Entirely
Two products are clearly off-limits during pregnancy:
- Castor oil can trigger intense uterine contractions. Despite folk remedies suggesting it to induce labor in overdue pregnancies, it increases the risk of meconium aspiration (where the baby inhales its first stool) and poses serious dangers to both mother and baby.
- Mineral oil interferes with the absorption of fat-soluble vitamins, particularly vitamin K. This can cause hemorrhagic disease in the newborn, a bleeding disorder. Mineral oil should not be used at any point during pregnancy.
Dietary and Lifestyle Changes That Help
Before reaching for any laxative, it’s worth optimizing the basics. Aim for 25 to 30 grams of fiber per day from whole foods: fruits, vegetables, beans, and whole grains. That’s roughly double what the average American actually eats. Prunes and pears are particularly effective, and many women find that a small glass of prune juice in the morning works as well as a mild laxative.
Hydration matters just as much as fiber. During pregnancy, your blood volume increases significantly, and your body needs more water than usual. Target 8 to 12 cups of water daily. Herbal teas and soups count toward that total. If you’re exercising less due to fatigue or discomfort, even light daily movement like a 20-minute walk can help stimulate your digestive system. The combination of adequate fiber, sufficient water, and regular movement resolves mild constipation for many women without any medication at all.
A Practical Order of Operations
Think of constipation management during pregnancy as a stepwise process. Start with dietary changes: more fiber, more water, more movement. If that’s not enough after a week or so, add a bulk-forming fiber supplement like psyllium. If stools are hard and painful, a stool softener like docusate sodium can help. For persistent constipation that doesn’t respond to these measures, an osmotic laxative like MiraLAX used occasionally is a reasonable next step. Stimulant laxatives are a last resort, and castor oil and mineral oil should never be on the list.
If you’re also taking iron supplements and struggling with constipation, ask your provider about switching to a different form of iron or adjusting the dose. Some prenatal vitamins use forms of iron that are easier on the gut, and this simple change can sometimes make the difference on its own.