Compatibility of Metformin and Pregnancy: How Safe Is the Treatment?

metformin and pregnancy

Metformin is a medicinal product of the biguanide class in the form of oral pills. It is designed to reduce blood sugar levels. Metformin is used in the treatment of type 2 diabetes, especially in overweight and obese people, while maintaining normal kidney function. The most famous trade names, under which metformin is produced are Metfogamma, Siofor and Glucophage. But what about Metformin and pregnancy? Are they compatible?

Metformin: Indications for Use

Diabetes mellitus type II (insulin-dependent) with ineffective diet, especially in patients with obesity:

  • As monotherapy or combination therapy with other oral hypoglycemic agents or together with insulin for the treatment of adults.
  • As monotherapy or combination therapy with insulin to treat children older than 10 years.

Keep in mind that the intake of Metformin only complements, but does not replace diet and physical activity.

Pharmacological Effect

Metformin improves the control of sugar in patients with type 2 diabetes. But sometimes it is prescribed for diabetes mellitus type 1 treatment. Metformin reduces sugar before eating, after eating, and over time improves blood test results for glycated hemoglobin HbA1C. The drug stimulates the liver to produce less glucose. It also affects the absorption of food carbohydrates in the digestive tract. What’s more, Metformin increases the sensitivity of cells to insulin. It does not stimulate the pancreas to produce extra insulin, so there is no risk of hypoglycemia.

metformin and pregnancy. Diabetes Drugs


The drug is excreted by the kidneys with urine. Absorption of active ingredient from long-acting tablets (Glucophage Long and analogs) is slow, compared to conventional pills. In people with impaired renal function, the concentration of the active substance in the blood plasma may increase, and this is not safe.


  • hypersensitivity to metformin and other biguanides;
  • diabetic ketoacidosis, diabetic precoma and coma;
  • chronic renal failure (at a serum creatinine level of more than 1.5 mg / dL in men and 1.4 mg / dL in women or creatinine clearance less than 60 ml / min);
  • violations of the liver;
  • conditions that can contribute to the development of lactic acidosis, including chronic heart failure, acute myocardial infarction, respiratory failure, acute impairment of cerebral circulation, dehydration, alcohol use;
  • lactic acidosis (including the one in the anamnesis);
  • hypocaloric diet (less than 1000 kcal / day);
  • pregnancy and lactation;
  • children’s age till 10 years;
  • the medicinal product is not prescribed 2 days before a surgery, radioisotope, X-ray studies with the introduction of contrast agents and within 2 days after these procedures.

Side Effects

Nervous system. Often: a violation of taste.

Digestive tract. Very often: nausea, vomiting, diarrhea, abdominal pain, lack of appetite, metallic taste in the mouth, flatulence. Most often, these side effects occur at the beginning of treatment and, as a rule, spontaneously disappear. To prevent the occurrence of side effects from the gastrointestinal tract, a slow increase in dosage and intake of the drug 2-3 times a day during or after a meal is recommended.

metformin and pregnancy. vomiting

Blood system: megaloblastic anemia.

Skin and subcutaneous tissue. Very rarely: skin rash, erythema, itching, urticaria.

Metabolism. Very rarely: lactic acidosis.

With prolonged use of the drug, absorption of vitamin B12 may decrease. As a result, there is a decrease in its level in the blood serum. Mostly, it occurs in patients with megaloblastic anemia.

Hepatobiliary system. Single cases: a violation of liver function or hepatitis, which completely disappear after the cancellation of Metformin.

Allergic reactions: very rarely – erythema, itching, skin rash.

In case of side effects, reduce or temporarily cancel the dose.

Metformin Risks and Side Effects

If you take Metformin correctly then the probability of risks and side effects are relatively low. However, some people still experience mild side effects. The most common of them are the following:

  • diarrhea
  • stomach pain
  • nausea
  • gastrointestinal changes
  • gas
  • heartburn

During pregnancy, these symptoms may make morning sickness worse. In order to prevent the appearance of side effects or reduce them, it is better to keep the lowest effective dose of the drug.

metformin and pregnancy. dizziness during pregnancy

Keep in mind that Metformin can reduce the blood sugar too much. This, in turn, may cause hypoglycemia. Symptoms of hypoglycemia include:

  • weakness and fatigue
  • confusion, drowsiness, or dizziness
  • fast heart rate, shaking
  • headache
  • irritation
  • hunger
  • sweating or chills

The risks of serious complications, such as lactic acidosis, are also possible because of Metformin. Lactic acidosis is caused by problems with the metabolism. The symptoms include the following:

  • stomachache
  • vomiting and nausea
  • irregular heart rate
  • dizziness, weakness, or feeling light headed
  • tiredness and fatigue
  • problems with breathing
  • muscle pains
  • difficulties with sleep

If you feel any serious symptoms or signs of lactic acidosis, immediately contact a doctor.

Warnings about Metformin and Pregnancy

According to experts, animal studies did not indicate harmful impact on pregnancy, fetal development, birth or postnatal development. Current data suggest that Metformin and pregnancy are compatible. However, this evidence is from observational or nonrandomized studies. Thus, one should interpret these data with caution. At the same time, many doctors still recommend insulin for treating type 1, type 2, and gestational diabetes (if the diet alone isn’t enough for controlling blood sugar).

metformin and pregnancy. woman taking meds

It is believed that the high glucose level in a woman during pregnancy is associated with maternal and fetal adverse effects. At the same time, long-term effects of Metformin in utero are unknown. What concerns Metformin and pregnancy, keep in mind that there are no well-controlled studies in pregnant women.

According to FDA US Metformin belongs to category B. It means that studies in animals did not demonstrate a risk to the fetus. But there are no adequate and well-controlled studies in pregnant women.

Thus, Metformin and pregnancy may be combined only if there is a real necessity.

Compatibility of Metformin and Pregnancy

All current studies show that Metformin has a low risk of complications during pregnancy. However, further clinical researches are still necessary.

There is also datum that Metformin and pregnancy are not only compatible but also useful. Some studies suggest that Metformin even has benefits for pregnant women and their babies when taken correctly. Keep in mind that only a doctor can prescribe the right dose of the medication.

According to some studies, taking Metformin during pregnancy is possible only if the expected positive effect of treatment exceeds the potential risk to the fetus. According to the FDA scale of possible risks to the fetus, Metformin is a drug classified as “B”. This means that animal studies did not reveal adverse effects on the fetus, but there are no well-controlled studies in pregnant women.

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