Metoprolol and Pregnancy
Studies that were conducted in pregnant rats showed an increased risk for postimplantation loss and death shortly after birth in doses up to 55 times the normal human dose. No birth defects were reported. It is important to note that animals do not always respond to medicines the same way that humans do.
Little human research has been conducted on the effects of metoprolol or any other beta blockers on the fetus. With other beta blockers, there have been individual reports of slowed intrauterine growth, small placentas, and birth defects in women who took metoprolol during pregnancy. There have also been reports of a very low heart rate, low blood sugar levels, and/or decreased breathing in some women when metoprolol was used during childbirth. It is important to note that there have been many women over the years who have taken this drug during pregnancy without any problems.
The animal research, along with sporadic cases of problems with other beta blockers during pregnancy, is why metoprolol has been given a classification of Category C. Metoprolol could potentially cause harm to your unborn child, but the exact risk is not known. This is why, in some situations, your healthcare provider will recommend the drug during pregnancy, and in other situations, he or she will not recommend it.
If you are pregnant or thinking of becoming pregnant while taking metoprolol, it is important to let your healthcare provider know. He or she will consider the benefits and risks before making a recommendation in your particular situation. Together, you and your healthcare provider can then decide what is best for you and your child.