Metformin or metformin hydrochloride is a prescription drug available as immediate-release or extended-release oral tablets for treating type 2 diabetes mellitus. Consuming metformin while pregnant helps lower blood glucose levels by improving the body’s response to naturally secreted insulin. It decreases the intestinal absorption of sugars from ingested food and controls the synthesis of sugars in the liver (1) (2). The drug also has proven benefits in treating polycystic ovary syndrome (PCOS) in women of reproductive age and improving pregnancy outcomes (3). Continue reading this post to learn about the safety and efficacy of metformin during pregnancy.
Is Metformin Safe During Pregnancy?
Metformin may be prescribed before or during pregnancy and is usually considered safe. Scientific studies have not suggested an increased incidence of any congenital anomaly with the use of this medication during pregnancy. The US Food and Drug Administration (FDA) ranks metformin in category B (animal reproduction studies have not demonstrated a fetal risk, and inadequate well-controlled studies have been conducted on pregnant women) (4).
How Does Metformin Help With Pregnancy?
Metformin may be prescribed by doctors when the body does not respond appropriately to the insulin hormone secreted by the pancreatic cells. This phenomenon is known as insulin resistance and is seen in type 2 diabetes mellitus and gestational diabetes (high blood glucose during pregnancy). The condition is also encountered in PCOS, a major cause of female infertility (5). Therefore, metformin may be beneficial before conception or during gestation in the following ways:
1. Fertility treatment of women with PCOS
PCOS is a common hormonal disorder (causing higher levels of male hormones) that negatively affects egg release from the ovary. Metformin alone or in combination with other medications can effectively induce ovulation, especially in non-obese women with PCOS. Additionally, metformin is considered useful in reducing the risk of ovarian hyperstimulation syndrome (painful swelling of the ovaries due to overstimulation) in women with PCOS undergoing in vitro fertilization (IVF) (6). Some studies also indicate that co-treatment with metformin may increase clinical pregnancy rates (7).
2. Treatment of gestational diabetes
Uncontrolled high blood glucose levels during pregnancy can negatively impact pregnancy. It may result in macrosomia, or a larger-sized baby, making a C-section necessary. The risk of miscarriage or stillbirths may also increase. Maternal complications may include high blood pressure, preeclampsia, and an increased risk of developing diabetes mellitus in the future (8). Though many doctors consider insulin the first-line treatment for gestational diabetes, current scientific evidence supports the safe use of metformin and dietary changes to control high blood sugar in pregnant women. Compared to insulin, metformin treatment has shown to cause less weight gain in pregnant women, and it is more patient compliant and cost-effective (4).
3. Treatment of pre-existing type 2 diabetes in pregnant women
Earlier, metformin was replaced with insulin when a woman with pre-existing type 2 diabetes got pregnant since doctors were unsure of its safety. However, several current studies show that metformin effectively controls hyperglycemia during pregnancy. Additionally, pregnant women receiving combination therapy of metformin and insulin require less insulin compared to insulin treatment alone (9).
What Is The Metformin Dosage In Pregnancy?
The dosage of metformin during pregnancy is best ascertained by your doctor based on your health requirements. However, metformin therapy for gestational diabetes usually begins with a dose of 500mg, which may be increased up to 2500mg, depending on how your body responds to it in terms of glycemic control and side effects (8).
Are There Side Effects Of Metformin?
The common side effects of metformin include (10) (11):
Nausea and vomiting Stomach cramps Bloating Diarrhea
Some adverse effects that are rare but may have more severe outcomes are:
Hypoglycemia or a sudden fall in blood glucose levels. Lactate build-up in the body, causing lactic acidosis. Pre-existing liver or kidney disorders increase its risk. Immediate medical attention is required in case of symptoms such as breathing troubles, shivering, fatigue, and muscle pain. Decreased vitamin B12 levels in the body due to long-term use.
What Are The Alternatives To Metformin In Pregnancy?
The following therapeutic agents may be used in cases where it is inappropriate to use metformin during pregnancy (8).
The American Diabetes Association recommends insulin for treating gestational diabetes. It is the standard therapy for the condition when dietary changes and exercise are insufficient to manage elevated blood sugar levels. Among oral antihyperglycemic agents, glyburide may be used in doses of 2.5mg to 20mg.
