To boost the odds of success, your doctor may transfer two to four embryos at a time. But this means you may get pregnant with twins, triplets, or even quadruplets. Carrying more than one baby raises the risk of miscarriage, anemia, high blood pressure, and other complications. It also makes premature birth more likely. It has become more common to transfer one embryo at a time to avoid these health risks. Talk about the risks with your doctor.