1 human pregnancy = 24,192,000 s ÷ 691,200 s per nundine = 35 → 35

• the Roman 8-day market week

1 human pregnancy = 24,192,000 s ÷ 88,775 s per Martian sol = 272.5 → 273

• a day on Mars

1 human pregnancy = 24,192,000 s ÷ 15,778,800 s per Friedman unit = 1.533 → 1.5

• six months, the perennial 'next six months'

1 human pregnancy = 24,192,000 s ÷ 1,209,600 s per fortnight = 20 → 20

• en.wikipedia.org

1 human pregnancy = 24,192,000 s ÷ 15,552,000 s per school year = 1.556 → 1.6

• ~180 days