Definition - What does Singleton Pregnancy mean?
A singleton pregnancy refers to a pregnancy with one fetus as opposed to twins/multiples. A singleton pregnancy results in fewer risks to the mother and fetus than pregnancies with multiples. As such, singleton pregnancy is usually the goal of treatment for infertility.
FertilitySmarts explains Singleton Pregnancy
Singleton pregnancies are associated with fewer risks to the mother than pregnancy with multiples. Risks to the mother from multiple gestations include an increased risk of pre-eclampsia, preterm labor, bleeding, anemia, cesarian section (C-section), and postpartum hemorrhage.
Risks to the fetuses in a multiple
Due to the increased risk of pregnancy with multiples, treatments for fertility issues aim to produce a singleton pregnancy. One way this can be achieved is using single embryo transfer (SET). By transferring just one embryo, the chances of multiple embryos implanting in the uterus are significantly reduced.
Allowing embryos to develop to the blastocyst stage (5 days after fertilization) prior to transferring is also thought to reduce the risk of multiples. This is because it allows embryologists to observe the developing embryos for a longer period of time. As a result, embryos can be graded for quality further along in their development. This means that the embryos with the best chance of producing a successful pregnancy can be transferred. This allows for the transfer of fewer embryos, thereby reducing the risk of multiples.