Why do some people describe pregnancy as lasting ten months?

[Overthemoun]

I have seen this a few times recently and I do not understand the thinking. Average is 40 weeks. 52 weeks in a year. 52/12=4.333. 40/4.333=9.231

Also, whilst they count your pregnancy as from your last period, it’s much more like 38 weeks.

Do the people in 10 month pregnancy have 13 month years?

So month 1 is weeks 0-4, month 9 is weeks 36-40, so if you go over 40 wks (38-42 is considered term) you are indeed in mth 10 of your pregnancy.

Who?

”Technically, pregnancy is closer to 10 months because it is measured in 40 weeks (280 days), which is closer to ten 28-day lunar months than nine 30/31-day calendar months. Because doctors count from the first day of the last menstrual period, the first two weeks occur before conception, creating a ~10-month, 40-week, or 280-day timeline”
That is why, apparently.

No we're not? The length of a pregnancy (from the last period to birth) is 40 weeks which is 9.23 months. If we measured from conception it would be closer to 9.