Flagyl (Metronidazole) use when pregnant

I have recently found out that I am about 4-5 weeks pregnant and my doctor had me take Flagyl (Metronidazole) for a infection I had. He prescribed it to me prior to knowing that I was pregnant. Well I missed a period and I went to the doctor and had a test done which said I was pregnant

My question is will that drug hurt my unborn child? My doctor said that it shouldn't harm the baby but on the bottle of pills it clearly states do not take if pregnant. Any information to this matter would be appreciated. I am 26 and this will be my third child.



Peg Plumbo CNM

Peg Plumbo has been a certified nurse-midwife (CNM) since 1976. She has assisted at over 1,000 births and currently teaches in the... Read more

Dear Kaye,

I wish I could convince all care givers to acknowledge that all drugs that they provide to women are potentially given to pregnant women. Why don't they consider what phase of the cycle a woman may be in or how likely a pregnancy would be before dispensing drugs. It will always be in the back of your mind throughout your entire pregnancy, no matter how much I try to reassure you, but try to be reassured anyway!

Metronidazole (Flagyl) has always had a warning label related to pregnancy because of high dose studies in animals that show that it may be a carcinogen and some birth defects were noted in rats.

These effects have never been seen in humans. It is a FDA Class B drug which means that no controlled studies have been done in pregnant women but no evidence of fetal risk appears to be present. (By the way, Tylenol is also a Class B drug).

In an article in the journal, "Obstetrics and Gynecology" in September, 1993, a study was reported which demonstrated no mutagenic or carcinogenic effects. Although it is still not recommended for use during the first trimester (very few drugs are), its use may helpful in preventing some of the complications (preterm labor and premature rupture of the membranes) that have been linked to bacterial infections such as bacterial vaginosis.

In addition, a statement from an article in the American Journal of Ob/Gyn, 2/95: "Metronidazole (Flagyl) is not generally used during 1st trimester but does not appear to be associated with an increased teratogenic (fetal defect) risk". Clindamycin vaginal cream or Metronidazole gel has been used in pregnancy with less systemic absorption.

Try not to worry, although concern is inevitable. I would be reassured by the studies.


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