Constipation ranks among the most commonly reported pregnancy symptoms and among the least commonly discussed. It rarely makes the list of things people mention when asked how pregnancy is going, yet research suggests it affects a substantial proportion of pregnant women — estimates commonly range from roughly a quarter to nearly half depending on definition and trimester.
For women over 35, several contributing factors can stack: hormonal effects on gut motility, iron supplementation, reduced activity as pregnancy progresses, and sometimes pre-existing digestive patterns. Understanding the mechanisms makes the situation feel less like a personal failing and more like predictable physiology.
This article describes what research indicates and what considerations commonly come up in prenatal care. It does not recommend specific treatments, since decisions about medications, supplements, and fiber during pregnancy belong with a healthcare provider.
What Research Shows About Pregnancy and Gut Motility
The primary mechanism described in the literature involves progesterone. Progesterone rises substantially during pregnancy and has a relaxing effect on smooth muscle throughout the body, including the smooth muscle of the intestinal wall.
Slower intestinal transit means stool spends longer in the colon, where water continues to be absorbed. The result is harder, drier stool that is more difficult to pass. This same smooth muscle effect contributes to other common pregnancy experiences, including reflux and, in the urinary tract, increased susceptibility to infection.
Later in pregnancy, mechanical factors add to the picture. The growing uterus displaces the intestines and can slow transit further. Resources from the American College of Obstetricians and Gynecologists describe constipation as a common pregnancy discomfort and discuss general approaches.
The Iron Supplement Factor
Iron supplementation is among the most frequently identified contributors. Iron deficiency and anemia are common in pregnancy, and supplementation is widely recommended, but oral iron is well documented to cause constipation, dark stools, and abdominal discomfort in a significant proportion of users.
Pregnancy after 35 may involve iron supplementation somewhat more often, given screening practices and the higher likelihood of prior pregnancies contributing to depleted stores. Women who have discussed iron status in the context of prenatal supplementation choices may already be aware of these tradeoffs.
Several variables are commonly discussed with providers when iron causes significant symptoms: the form of iron, the dose, whether alternate-day dosing might be appropriate, and timing relative to meals. Research in recent years has examined alternate-day dosing with interesting findings regarding absorption. These are prescriber decisions rather than adjustments to make independently, since adequate iron matters for both pregnancy and postpartum recovery.
Other Contributing Factors
- Reduced physical activity, particularly in later trimesters or with activity restrictions
- Nausea and vomiting in early pregnancy affecting fluid and fiber intake
- Dietary changes, including food aversions that reduce vegetable and whole grain intake
- Dehydration, which pregnancy increases requirements for
- Certain antacids, particularly those containing calcium or aluminum
- Pre-existing conditions, including irritable bowel syndrome and hypothyroidism
- Ondansetron and some other medications used for pregnancy nausea
Thyroid function deserves mention, since hypothyroidism is associated with constipation and thyroid screening is common in pregnancy. Women who later encounter symptoms described in overviews of postpartum thyroid changes sometimes find digestive symptoms were part of a broader pattern.
Approaches Commonly Discussed in Prenatal Care
General guidance for pregnancy constipation typically begins with dietary and lifestyle measures, with medications considered when those are insufficient.
Fiber and Fluid
Dietary fiber from fruits, vegetables, legumes, and whole grains adds bulk and retains water. Increasing fiber without increasing fluid can worsen symptoms, which is why the two are generally discussed together. Adding fiber gradually rather than abruptly is commonly suggested to reduce bloating and gas.
Movement
Regular physical activity is associated with improved bowel function in general populations. Walking is frequently suggested during pregnancy, though any activity plan should account for individual circumstances and any restrictions a provider has advised.
Toileting Habits
Responding to the urge rather than deferring, allowing unhurried time, and positioning with knees elevated are commonly discussed practical measures. Straining is generally discouraged, partly because of its association with hemorrhoids, which pregnancy already predisposes toward.
Medications and Supplements
Several categories of laxatives exist, including bulk-forming agents, osmotic agents, stool softeners, and stimulants. They differ in mechanism, onset, and how much pregnancy-specific safety data exists. Because of these differences, deciding what is appropriate is a conversation with a provider or pharmacist rather than a matter of general recommendation. Some products commonly used outside pregnancy are generally avoided during it.
When to Contact a Healthcare Provider
Constipation is usually a discomfort rather than a danger, but certain features generally warrant a call:
- No bowel movement for several days despite dietary measures
- Severe abdominal pain or cramping
- Rectal bleeding, or blood in stool
- Alternating constipation and diarrhea
- Nausea and vomiting alongside inability to pass stool or gas
- Unexplained weight loss
- Symptoms of hemorrhoids or anal fissure causing significant pain
Some rectal bleeding during pregnancy relates to hemorrhoids and is not dangerous, but it should be evaluated rather than assumed.
Postpartum Continuation
Constipation frequently persists or worsens in the early postpartum period. Contributing factors include pain medications, particularly opioids after cesarean birth, iron supplementation continuing, dehydration during establishment of breastfeeding, perineal pain or a cesarean incision creating apprehension about straining, and reduced mobility.
The first postpartum bowel movement is a commonly reported source of anxiety, and many hospitals routinely offer stool softeners for this reason. Raising it before discharge rather than after is often easier.
Distinguishing Constipation From Other Pregnancy Symptoms
Abdominal discomfort during pregnancy has many possible sources, and constipation is only one. Round ligament pain, Braxton Hicks contractions, gas, and urinary tract infection can all produce sensations that overlap. Later in pregnancy, upper abdominal pain in particular warrants attention because it can relate to blood pressure conditions rather than digestion.
Providers generally ask about the pattern: where the discomfort sits, whether it comes and goes, whether it relates to bowel movements, and what accompanies it. Being able to describe those details tends to shorten the path to an answer.
Women receiving additional monitoring in the third trimester sometimes find that digestive symptoms are reviewed alongside other findings, since several pregnancy conditions produce nonspecific abdominal complaints. Reporting symptoms plainly, without deciding in advance whether they are important enough to mention, is generally the more useful approach.
Frequently Asked Questions
Is constipation an early sign of pregnancy?
Rising progesterone begins affecting gut motility early, and some women notice changes before other symptoms. However, constipation has many causes and is not a reliable indicator on its own.
Should I stop taking iron if it causes constipation?
Iron is generally recommended for good reasons during pregnancy, and stopping without discussion may leave a deficiency untreated. A provider may be able to adjust form, dose, or schedule instead.
Are over-the-counter laxatives safe during pregnancy?
Different categories have different safety profiles and different amounts of pregnancy-specific data. Checking with a provider or pharmacist before using any product is generally advised.
Can straining harm the pregnancy?
Straining is generally uncomfortable rather than dangerous to the pregnancy, but it is associated with hemorrhoids and anal fissures. Persistent difficulty is worth addressing rather than enduring.
Key Takeaways
- Rising progesterone slows intestinal transit, and mechanical pressure from the growing uterus adds to this later in pregnancy.
- Oral iron supplementation is a frequently identified contributor, and form, dose, and timing can sometimes be adjusted by a prescriber.
- Fiber, fluid, and movement are generally discussed first, with fiber increased gradually alongside fluid.
- Severe pain, rectal bleeding, or inability to pass stool or gas warrant prompt contact with a healthcare provider.
- Constipation commonly continues postpartum, and raising it before hospital discharge is often easier than afterward.
Medical Disclaimer
This content is for informational purposes only and does not constitute medical advice. Individual health situations vary significantly. Always consult a qualified healthcare provider before making decisions related to your health, fertility, or pregnancy.
About the Author
Emily Carter is a women’s health writer focused on fertility, pregnancy after 35, and sleep changes in midlife. She writes research-informed, non-alarmist content to help women navigate reproductive and hormonal transitions with clarity and confidence.