Most people can know for sure whether they are having twins at the first- trimester ultrasound, usually between about 6 and 12 weeks of pregnancy, when two gestational sacs or two embryos can be seen. Before that, there can be clues (like very high hCG levels or stronger-than-expected symptoms), but these are not definite without an ultrasound.

How early twins can be confirmed

An ultrasound can often detect twins as early as around 6–7 weeks of pregnancy, when separate sacs or embryos may be visible. If routine scans are later in your area, twins are usually clearly seen by the standard first- trimester scan done between about 8 and 14 weeks.

Early signs vs certainty

Some people with twin pregnancies have more intense nausea, fatigue, faster weight gain, or feel “bigger” than expected, but these symptoms can also happen with a single baby. Blood tests may show higher-than-average hCG levels for gestational age, which can raise suspicion for twins, but this still needs ultrasound confirmation.

When to contact a clinician

If you have a positive pregnancy test and suspect twins because of very strong symptoms or a history of twins, it is reasonable to ask your clinician whether an earlier ultrasound is appropriate. Seek urgent care if you have severe pain, heavy bleeding, or cannot keep fluids down, regardless of whether it might be a twin pregnancy.