week 24 fetal viability threshold
A complete week 24 corresponds to 168 days of gestation counted from the LMP, still within this calculator's 2nd trimester (which runs through day 195). This page explains what that counting milestone represents and why it is not, by itself, a prognosis: viability thresholds are set by each health service and vary from country to country, and it is the medical team who evaluates each individual case.
Falls within what the WHO calls extremely preterm (before week 28). Clinical decisions at this point belong to the neonatal care team, not to this calculator.
Marks the start of what the WHO calls very preterm (week 28 up to before 32), and also the internal cutoff this calculator uses for the 3rd trimester.
Marks the start of what ACOG calls early term (37 weeks to 38 weeks 6 days). In ACOG's classification, full term only begins at week 39, and postterm begins at week 42.
The gestational count starts at the LMP by universal medical convention, because the exact date of ovulation and fertilization is rarely known precisely. This means that in the first two gestational weeks, pregnancy has not yet occurred biologically, ovulation and fertilization typically happen in weeks 2–3.
No. The calculator only counts days and weeks from the LMP, it has no survival-statistics field and does not assess weight, clinical condition or hospital resources. Any decision about viability in a real case belongs exclusively to the responsible medical team.
Because they depend on neonatal intensive care resources, local protocols and each baby's clinical condition, factors that a week count alone does not capture. The WHO's week-range classification describes categories of prematurity, it does not guarantee an individual outcome.
Yes, because the entire count starts from whichever reference date is entered. If an ultrasound reports a gestational age different from the LMP-based one, see the ultrasound gestational age calculator to convert that result into a new reference date before comparing weeks.
Medical notice: this calculation is educational, based on population-level averages, and does not replace prenatal care, ultrasound, diagnosis or guidance from a doctor or obstetrician.
The date you enter stays in your browser only. We do not save or send this data.