Question

A pregnant female comes to a gynecologist who sends her for USG. On USG twin pregnancy noted with about one month difference in age of fetuses. Which is true of following

• A. Superfetation
• B. Superfecundation
• C. Suppositious child
• D. Posthumous child

Hint:

Two fetuses one month apart in age means the second ovum was fertilised in a later menstrual cycle – which single term describes that?

Answer 1

The Correct Option is A

Step 1: Identify the key finding. The ultrasound shows two fetuses that differ in gestational age by about one month. The question is which medico-legal term explains two co-existing fetuses of clearly DIFFERENT ages in the same uterus.

Step 2: Define the terms.
• Superfetation: Fertilisation of a SECOND ovum and implantation of a second embryo when a pregnancy already exists, i.e. conception in two different menstrual cycles. The two fetuses therefore differ in age by about a month - exactly what the scan shows.
• Superfecundation: Fertilisation of TWO ova released in the SAME cycle by sperm from two separate acts of coitus (often two different men). Both fetuses are of the SAME age - they do not differ by a month.
• Suppositious child: A medico-legal fraud where a child is falsely passed off as having been born to a woman who was never pregnant (pretended delivery). It is not about twin ages.
• Posthumous child: A child born after the death of its father (born from a pregnancy already established before the father died). Not about age difference between twins.

Step 3: Match to the scenario. A difference of roughly one month in fetal age means the two ova were fertilised in two different menstrual cycles → this is the definition of superfetation.

Step 4: Eliminate distractors. Superfecundation (B) gives same-aged twins, so it is wrong. Suppositious child (C) and posthumous child (D) deal with parentage/legitimacy fraud and timing of birth relative to the father's death, not the age gap between twins.

Final answer: A - Superfetation.