Can a colonoscopy cause a miscarriage?

Studies have not shown that colonoscopy causes miscarriage, but the studies are small. A large Swedish registry study found no link between endoscopy in pregnancy and stillbirth or birth defects. Doctors still limit the procedure to strong reasons and prefer the second trimester.

Is a colonoscopy in the first trimester dangerous?

There is less data for the first trimester, so the ASGE guideline advises waiting for the second trimester when possible. The guideline also notes that propofol safety in the first trimester has not been well studied. If bleeding is serious, doctors may still scope early with extra care.

Do I need to tell the clinic I might be pregnant?

Yes. Tell the clinic about any chance of pregnancy before you start the prep. It changes the choice of prep, sedation, positioning, and monitoring, and it may change whether the test happens at all.

Can I do a colonoscopy right after giving birth?

Many people can, since pregnancy-related limits no longer apply after delivery. If you are breastfeeding, ask which sedation drugs will be used and how long to wait before nursing. Your doctor may also want you to recover from delivery before a screening exam.

Is a sigmoidoscopy safer than a colonoscopy in pregnancy?

A sigmoidoscopy looks only at the lower colon, is shorter, and often needs only enemas instead of a full prep. A 1996 multi-center study found it useful for rectal bleeding in pregnancy with no procedure complications. Your doctor will choose based on where the problem likely is.

Is It Safe to Have a Colonoscopy While Pregnant?

The short answer: It can be, but only for a strong reason. The 2012 ASGE guideline on endoscopy in pregnant and lactating women says to do it only with a strong indication, such as significant bleeding, and to wait for the second trimester when possible. Routine screening should wait until after delivery.

How safe is a colonoscopy during pregnancy?

The honest answer is that the data are thin, but they are reassuring. Pregnant women are rarely scoped, so most studies are small. The ASGE guideline notes that studies of colonoscopy in pregnancy "involve very small numbers," which limits the ability to detect uncommon problems.

The largest study comes from Sweden. A 2017 nationwide cohort study in Gastroenterology linked birth and patient registries from 1992 to 2011. It found 3,052 pregnancies exposed to endoscopy, including 1,109 lower endoscopies. Here is what it showed:

Endoscopy during pregnancy was not linked to birth defects or stillbirth.
It was linked to a higher risk of preterm birth (adjusted relative risk 1.54) and a small-for-age baby (1.30).
When the researchers left out women with inflammatory bowel disease, celiac disease, or liver disease, the link to preterm birth went away (1.03).
Comparing two births to the same mother, only one exposed, showed no link with birth weight or gestational age.

The authors concluded the risks are small and likely come from the underlying disease, not the scope. That matters. An active colitis flare can harm a pregnancy on its own.

Smaller studies point the same way. A 2010 study of 20 pregnant women who had colonoscopy compared them with 20 matched pregnant women who did not. Fetal outcomes were similar or better in the colonoscopy group. Two mothers had mild, short drops in blood pressure. The results changed treatment in 35% of patients.

When do doctors do a colonoscopy during pregnancy?

Only when the answer will change care and cannot wait. The ASGE guideline lists these reasons for endoscopy in pregnancy that apply to the colon:

Significant or continued bleeding from the digestive tract.
Strong suspicion of a colon mass.
Severe diarrhea when other tests found no cause.
Severe or hard-to-treat abdominal pain.

A suspected flare of ulcerative colitis or Crohn's disease is a common real-world reason. In the 2010 study, colonoscopy found ulcerative colitis in 5 women and Crohn's colitis in 2.

Doctors often start smaller. A flexible sigmoidoscopy looks at only the lower colon and rectum. A 1996 study across 10 medical centers reviewed 48 sigmoidoscopies in pregnancy. It found a significant cause in 22 of 29 women with rectal bleeding and no procedure complications. The authors suggested saving full colonoscopy for life-threatening bleeding or when the only other option is surgery.

The guideline says endoscopy should not be done with placental abruption, imminent delivery, ruptured membranes, or uncontrolled eclampsia. If you have new rectal bleeding and want to sort out how urgent it is, symptom.md covers when symptoms need same-day care.

What changes during the procedure if you are pregnant?

The scope is the same. The setup around it changes. Per the ASGE guideline:

Your obstetrician is involved first. Every procedure needs a consult with an obstetrician, at any stage of pregnancy.
Timing moves to the second trimester when possible. In the 2010 study, 16 of 20 colonoscopies were done in the second trimester.
You lie on your left side. In the second and third trimesters, you should not lie on your back before, during, or after the procedure. The uterus can press on major blood vessels and lower blood flow to the placenta. A wedge under the right hip helps.
The baby is checked. Before 24 weeks, a Doppler check of the fetal heart rate before sedation and after the procedure is enough. After 24 weeks, the fetal heart and contractions are monitored before and after. Ideally the hospital has neonatal care on site.
Sedation is kept light. The guideline uses the lowest effective dose. For moderate sedation it prefers meperidine, with small amounts of midazolam if needed. Deeper sedation, such as propofol, should be given by an anesthesia provider. Our guide to being awake for a colonoscopy explains the sedation levels.
The procedure is kept short. If the nurse needs to press on your belly, the pressure should be mild and aimed away from the uterus.
Polyp removal usually waits. Amniotic fluid can conduct electric current. The guideline says polyp removal with electrocautery should be postponed until after delivery.

Is bowel prep safe during pregnancy?

This is the least studied part. The ASGE guideline states that the safety of polyethylene glycol (PEG) prep solutions "has not been studied in pregnancy." It warns that sodium phosphate preps can cause fluid and electrolyte problems and should be used with caution.

The FDA label for GoLYTELY, a PEG prep, says animal studies were not done. It says the prep should be given to a pregnant woman only if clearly needed. The label also says it is not known whether the drug passes into breast milk.

You may see older letter grades, such as "category C," in articles. The FDA Pregnancy and Lactation Labeling Rule removed those letter categories from prescription labels. Newer labels give a written risk summary instead.

For a sigmoidoscopy, the guideline says tap water enemas may be enough. Ask whether a full prep is truly needed. Do not choose or change a prep on your own. Our colonoscopy prep guide explains how the common preps work. Also bring a full list of your prenatal vitamins and medicines, and review which medications to stop before colonoscopy with your care team.

Should screening wait until after delivery, and can you breastfeed after sedation?

Yes, screening should wait. Screening is not on the guideline's list of reasons to scope a pregnant woman. The 2021 USPSTF recommendation starts average-risk screening at age 45, so a short delay rarely matters. If you have a family history or symptoms, tell your doctor. Symptoms are not screening.

Breastfeeding is usually possible after a colonoscopy. The ASGE guideline suggests:

Fentanyl: breastfeeding may continue.
Propofol: breastfeeding may continue once you are awake enough to nurse.
Midazolam: wait at least 4 hours before nursing.
Meperidine: it concentrates in breast milk and can be detected up to 24 hours later. The guideline favors another drug, such as fentanyl, when possible, especially with a newborn or preterm baby.

If there is a concern about a drug, the guideline says to pump and discard milk for the right time after the procedure. Pumping before your appointment gives you a stored supply.

What should you ask before a colonoscopy while pregnant?

Use this checklist, built from the ASGE guideline, at your consult:

Why is it needed now, and what happens if we wait until the second trimester or after delivery?
Would a flexible sigmoidoscopy answer the question instead?
Has my obstetrician reviewed the plan?
How will you check the baby's heart rate, and will contractions be monitored?
Does this hospital have neonatal care on site?
Which sedation will I get, and who will give it?
Which bowel prep do you want me to use, and is a full prep required?
How will you keep me off my back during and after the procedure?
If you find a polyp, will you remove it now or after delivery?
If I am breastfeeding, how long should I wait before nursing?

The bottom line

A colonoscopy during pregnancy is not routine, but it is not forbidden. The ASGE guideline limits it to strong reasons, such as significant bleeding, and favors the second trimester. A Swedish study of 3,052 pregnancies exposed to endoscopy (1,109 of them lower endoscopies) found no link to birth defects or stillbirth. Plan screening for after delivery. If you need a scope sooner, ask about your obstetrician's role, fetal monitoring, sedation, prep, and nursing.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. If you are pregnant or breastfeeding and need a colonoscopy, make the plan with your gastroenterologist and obstetrician together.