The lunar month and gestation

[Luis Gonzalez-Reimann]

At 07:38 AM 5/30/97 BST, Martin gansten wrote:
>Luis Gonzalez-Reimann writes:

>>The average duration of pregnancy is about 280 days, or 40 weeks of 7 days.
>
>Well, no, not if you mean the actual period of gestation; the average would
>actually be about 38 weeks, as reckoned from the time of conception (though
>there is plenty of scope for individual variation). The 40 week average
>refers to the time of pregnancy as reckoned from the first day of the
>mother's last period, which is more easily discernible; conception is
>supposed to take place two weeks thereafter.

You are right.  But I think that what is relevant in the present context is
what is discernible, as you say.  In other words, what was probably observed
when we read that 10 months are the gestation period.
Actually, even today it is not uncommon to say that gestation lasts for 10
lunar months of 28 days (as I discovered years ago when getting ready for
the birth of my children).

This is from the online Britannica:


                        "gestation...in mammals, the time between conception
and birth,                       during which the embryo or fetus is
developing in the uterus. This
                       definition raises occasional difficulties because in
some species
                       (e.g., monkeys and man) the exact time of conception
may not
                       be known. In these cases the beginning of gestation
is usually
                       dated from some well-defined point in the
reproductive cycle
                       (e.g., the beginning of the previous menstrual period)."

Best,

Luis