Among many other complications we hear during pregnancy Gestational Diabetes Mellitus (GDM) stands tall as Metformin for treating it. The increase in PCOS/PCOD conditions in women in recent times and increasing obesity in women are high predisposing factors for Gestational Diabetes in pregnant women. Once diagnosed there is no escape other than using the medication to control GDM along with a good diet and exercise.
But not to worry Metformin can play its role. All we need to know is little information about Metformin, how it helps control gestational diabetes, its effect on the fetus, its impact on the mother, any side effects, precautions to be taken while using metformin, and how long it should be used.
What is Metformin?
Metformin is widely used for treating and preventing type 2 Diabetes. This medicine is also combined with other diabetic medications for better control of blood glucose. Along with type 2 Diabetes Metformin is used for treating Gestational Diabetes and Polycystic Ovarian Syndrome (PCOS). There are many more uses for metformin which are under research. (1)
Is It Safe To Take Metformin During Pregnancy?
Taking metformin during pregnancy is considered safe for the mother and baby. Metformin does not increase the chance of any congenital abnormalities in the fetus (2). There are no adverse side effects that can affect the mother and baby.
Women with Gestational Diabetes show less increase in weight with Metformin than insulin. Women with uncontrolled gestational diabetes are prescribed both metformin and low doses of insulin. It is more beneficial for women who are already obese for less weight gain in gestational diabetes.
Women who are type 2 diabetic and taking metformin should continue doing so. Insulin is only added when the desired blood sugar values are not achieved. Women taking metformin for PCOS and continuing till the last term of pregnancy have reduced the risk of Gestational Diabetes, Hypertension, and Preterm labor. Taking Metformin can also prevent early pregnancy loss, fetal growth retardation. (3)
What Should Be the Dosage of Metformin?
If your HbAIc is greater than 5.7% and fasting levels are more than 93mg/dl- 95mg/dl consistently, you are considered to have Gestational Diabetes and initially, you may be advised to take Metformin.
- The usual recommended dosage for Gestational Diabetes is Tab Metformin 500mg once daily or twice daily.
- If the blood sugar targets are not achieved the dose may be increased to 2gm to 2.5gm or Metformin is combined with any other Anti-diabetic medication.
- In case of insulin initiation to achieve targeted blood sugar levels metformin may also be added along with the insulin. (1a)
Can Metformin Cause Birth Defects?
Metformin use by Mother: Metformin crosses the placental freely. Yet no evidence or research supports taking Metformin by a mother for Gestational Diabetes increases the chances of birth defects in the fetus.(4)
Metformin use by Father: The role of Metformin in causing birth defects, especially among boys is present when fathers take metformin (for conditions like type 2 Diabetes )during the first three months before conception.
The reason is, that taking Metformin before conception affects sperm development and maturation. If conceived this can lead to serious birth defects in a boy child than in a girl child and can lead to miscarriage when conceived. (5)
Precautions Of Taking Metformin During Pregnancy?
As Metformin is taken to reduce blood glucose levels, there are certain precautions while taking metformin during pregnancy :
- Take only recommended dosage- no high no low. In case of a missed dose take the next dose on time and continue the medication. Do not double the dose.
- If you have any known kidney or liver diseases please inform your doctor before taking Metformin
- Inform your doctor about any sudden weight gain or weight loss during pregnancy after starting using Metformin
- Do not stop or start metformin suddenly without doctors suggestion.
In case of any doubts please consult your doctor to take further precautions.
Side Effects Of Metformin During Pregnancy?
Metformin is well tolerated throughout the pregnancy with no increase of adverse side effects. Yet there may be few side effects in using Metformin (3),(1)
- The most common side effects are Nausea, diarrhea, and vomiting.
- General weakness, headache.
- Hypoglycemia -low blood glucose levels
- Prolonged use of Metformin may decrease Vit B12 levels which are crucial for pregnancy. Your doctor will add a supplement of B12 to maintain the levels.
- Metformin exposure in mothers may contribute to childhood obesity and diabetes in later life in few children
If you observe any other additional side effects please notify your doctor.
Is It Safe If I Took Metformin Before Conception?
Metformin before conception is given for treating Polycystic Ovarian Disorder/Syndrome if diagnosed. You also might be taking metformin to manage type 2 diabetes if you already have it. Most of the women get confused about whether to continue metformin after conceiving or not. Well, there are many studies suggesting taking metformin for PCOS can significantly reduce gestational diabetes (6) Even if you are taking it for managing type 2 diabetes it’s required to continue for the well-being of the mother and baby.
Metformin During Breastfeeding
Metformin can pass through breast milk in very low amounts. Your baby may not have any effects from Metformin in such low amounts and can be healthy. But having said that newborns, premature infants, and renal impaired babies should need caution on using Metformin by mothers Please follow your doctor’s recommendation (7).
Alternatives To Metformin During Pregnancy
Two alternatives are frequently used for Metformin. Insulin and Glyburide.
1. Insulin
Taking Insulin is always a gold standard option for Gestational Diabetes as it mimics the body’s production of insulin and does not cross the placenta. Hence no risk of congenital birth defects in the baby. The only risk for mothers is frequent hypoglycemia and dose adjustments are often needed. It can be taken by breastfeeding mothers also as it doesn’t pass through mother milk.
Another drawback of Insulin is its suboptimal compliance by many pregnant women favoring taking tablets over injections (8).
2. Glyburide
It is also a drug like metformin and acts as an Antidiabetic agent. The advantage being that does not cross the placenta but the hypoglycemia side effect is more or less equal to insulin. Glyburide does not decrease the birth weight of the newborn as in the case of Metformin. The remaining effects are more or less the same as Metformin. (8)
Metformin is prescribed both for PCOS and Gestational Diabetes. Taking Metformin helps in many ways to keep a check on complications arising from gestational diabetes like preterm labor, increased risk of cesarean, gestational hypertension, etc. It can also be beneficial for neonates to avoid hypoglycemia, hypocalcemia prenatal deaths, etc. Most of the research says Metformin is safe and does not increase the risk of birth defects in newborns except for the low birth weight and neonatal hypoglycemia in a few newborns. Nonetheless, you need to manage mild side effects and maintain proper levels of Vitamin B12. Please follow the doctor’s recommendations regarding dose and dosage.
FAQ’s
1. Why is Metformin Given During Pregnancy?
Metformin is given to increase the insulin sensitivity in PCOS to prevent early miscarriage and to help regulate the blood sugar levels in case of Gestational Diabetes and to avoid preterm labor.
2. When You Should Stop Taking Metformin During Pregnancy?
Metformin is safe and has many benefits especially if you are having Gestational Diabetes. You should not stop taking Metformin unless recommended by the doctors.
3. How Much Metformin Is Safe During Pregnancy?
The general dosage of Metformin is 500mg to 2500 mg per day depending on your targeted blood sugar levels.
4. What Is The Best Treatment For Diabetes In Pregnant Women?
Taking insulin is the best treatment for Gestational Diabetes as it doesn’t cross the placenta and present in the breast milk. Your doctor may also recommend oral medications such as Metformin as a combination therapy.
References
- Calette Corcoran; Tibb F. Jacobs. University of Louisiana Monroe – https://www.ncbi.nlm.nih.gov/books/NBK518983/
- Verma V, Mehendale AM. A Review on the Use of Metformin in Pregnancy and Its Associated Fetal Outcomes. Cureus. 2022 Oct 7 – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9637404/
- Hyer S, Balani J, Shehata H. Metformin in Pregnancy: Mechanisms and Clinical Applications. Int J Mol Sci. 2018 Jul 4;19(7):1954. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073429/
- Given JE, Loane M, Garne E, Addor MC, Bakker M, Bertaut-Nativel B, Gatt M, Klungsoyr K, Lelong N, Morgan M, Neville AJ, Pierini A, Rissmann A, Dolk H. Metformin exposure in first trimester of pregnancy and risk of all or specific congenital anomalies: exploratory case-control study. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016021/
- Wensink MJ et al. Preconception antidiabetic drugs in men and birth defects in offspring. Annals of Internal Medicine – https://www.nichd.nih.gov/newsroom/news/033122-metformin-birth-defects
- Bidhendi Yarandi R, Behboudi-Gandevani S, Amiri M, Ramezani Tehrani F. Metformin therapy before conception versus throughout the pregnancy and risk of gestational diabetes mellitus in women with polycystic ovary syndrome: a systemic review, meta-analysis and meta-regression. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6651943/
- Drugs and Lactation Database (LactMed®) [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006 – https://www.ncbi.nlm.nih.gov/books/NBK501020/
- Kalra B, Gupta Y, Singla R, Kalra S. Use of oral anti-diabetic agents in pregnancy: a pragmatic approach. N Am J Med Sci. 2015 Jan – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4325398/
