The World Health Organization (WHO) classifies maternal deaths by timing relative to the end of pregnancy. A maternal death is the death of a woman while pregnant or within 42 days of termination of pregnancy, from causes related to or aggravated by the pregnancy or its management. Beyond this, WHO also defines a late maternal death as the death of a woman from direct or indirect obstetric causes occurring more than 42 days but less than one year after termination of pregnancy.
The 42-day (6-week) cut-off corresponds to the standard duration of the puerperium (postpartum period), during which the mother's reproductive organs return to their pre-pregnancy state. WHO uses this same 42-day boundary to separate "maternal death" (occurring within 42 days) from "late maternal death" (occurring after 42 days but before one year), because obstetric complications such as puerperal sepsis, embolism, or pregnancy-related cardiomyopathy can still cause death well after the immediate postpartum window, and capturing these within one year gives a fuller picture of maternal mortality.
Hence, the correct value of X is 42, consistent with WHO's official definition of late maternal death.