Can one embryo transfer result in twins?

A transferred embryo may implant and continue developing as a single pregnancy, or it may split after transfer and develop into identical twins. The number of embryos placed in the uterus does not always equal the number of babies seen later. An ultrasound can show whether there is one gestational sac, more than one sac, or developing babies sharing structures. Shared placental or sac arrangements can affect monitoring, so your maternity team will explain the findings as they become clear.

Keep the scan appointments arranged by your fertility or maternity team and take prescribed medicines exactly as directed. If micronised progesterone has been prescribed, do not stop it without speaking with the prescriber. Record bleeding, pain, dizziness, or changes in symptoms so you can describe them accurately. Twin pregnancy may require closer checks of growth, blood pressure, and other pregnancy changes; your clinician will tailor the schedule to the scan findings.

Contact your fertility clinic or maternity service promptly for heavy bleeding, worsening one-sided abdominal pain, fainting, severe shoulder-tip pain, or breathlessness. Seek emergency help for collapse, severe pain, or difficulty breathing. These symptoms need assessment because early pregnancy complications can occur whether one or two babies are developing.

Ask when the next ultrasound should take place, whether the babies appear to share a placenta or sac, which warning symptoms should prompt a same-day call, and how your medicines should be continued.