How does weeks work in pregnancy ?

Mandy 🇵🇷 🗽

I’m almost 24 weeks but I count the pregnancy four weeks in each month but they say six months Can last for seven weeks and start between 21 weeks and ends on the 28th. 21 weeks to 28 weeks would accumulate to seven months pregnant and nine months at 40 weeks 🙄 But does that mean that every other month has four weeks?