README file for Date-Pregnancy
$Id$
NAME
Date::Pregnancy - calculate birthdate and week numbers for a pregnancy
SYNOPSIS
use Date::Pregnancy qw(calculate_birthday);
my $dt = DateTime->new(
year => 2004,
month => 3,
day => 19,
);
$birthday = calculate_birthday(first_day_of_last_period => $dt);
$birthday = calculate_birthday(
first_day_of_last_period => $dt,
period_cycle_length => 28,
);
use Date::Pregnancy qw(calculate_week);
$week = calculate_week(first_day_of_last_period => $dt);
$dt2 = DateTime->new(
year => 2004,
month => 12,
day => 24,
);
$week = calculate_week(
first_day_of_last_period => $dt,
date => $dt2,
);
$week = calculate_week(
first_day_of_last_period => $dt,
method => '40weeks',
);
$week = calculate_week(birthday => $birthday);
use Date::Pregnancy qw(calculate_month);
$month = calculate_month(first_day_of_last_period => $dt);
$month = calculate_month(
first_day_of_last_period => $dt,
date => $dt2,
);
$month = calculate_month(
first_day_of_last_period => $dt,
method => 'countback',
);
$week = calculate_month(birthday => $birthday);
DESCRIPTION
This module can be used to calculate the due date for a pregnancy, it
implements 3 different methods, which will give different results.
The different methods are described below in detail (SEE: METHODS).
This module relies heavily on DateTime objects in order to calculate
dates of birth, week numbers and month numbers. It does however not
require Michael Schwern's module Sex.
calculate_birthday
Calculates date of birth.
Takes one named parameter:
* first_day_of_last_period
Which should be a DateTime object indicating the first day of the last
period.
If the period cycle length varies from the average og 28 days, you can
optionally provide the named parameter:
* period_cycle_length
This defaults to 28.
The default method used for calculating date of birth is the 266 days
method (SEE: Methods). If you want to use one of the other methods you
can use the named parameter method and specify either:
* 40weeks
* countback
The function returns a DateTime object indicating the calculated day of
birth or undef upon failure.
calculate_week
Calculates in what week the pregnant person currently is. A pregnancy is
in average 40 weeks these weeks numbers are normally used when talking
pregnancy and most guides, books and websites refer to the different
stages of pregnancy using these week numbers.
Takes one named parameter:
* first_day_of_last_period
Which should be a DateTime object indicating the first day of the last
period.
Optionally you can provide it with a named date parameter if you want to
calculate the week number for a given date. The date specified should be
a DateTime object, this defaults to now, when not provided.
Also a named parameter called birthday can be provided, if you already
have an birthday DateTime object. If this is not provided calculate_week
will call calculate_birthday internally.
As for calculate_birthday the function also takes the named paramter:
* first_day_of_last_period
and
* method
Please refer to calculate_birthday.
The function returns an integer indicating the week of the pregnancy or
undef upon failure.
calculate_month
Calculates in what month the pregnant person currently is (see also
calculate_week). A pregnancy is in average 9 months.
Takes one named parameter:
* first_day_of_last_period
Which should be a DateTime object indicating the first day of the last
period.
Optionally you can provide it with a named date parameter if you want to
calculate the month number for a given date. The date specified should
be a DateTime object, this defaults to now, when not provided.
Also a named parameter called birthday can be provided, as for
calculate_week, if you already have an birthday DateTime object. If this
is not provided calculate_month will call calculate_birthday internally.
As for calculate_birthday the function also takes the named paramter:
* first_day_of_last_period
and
* method
Please refer to calculate_birthday.
The function returns an integer indicating the month of the pregnancy or
undef upon failure.
METHODS
This module implements 3 different methods for calculating the date of
birth based on data such as first day of last period (LMP) and average
period cycle length (APCL).
The 3 methods are:
266 Days (the one used by default)
40 Weeks
Count Back
266 Days
This method uses the APCL together with the LMP.
It adds the APCL divided by 2 to the LMP in the case where APCL is equal
to or lower than the average of 28 days.
In the case where the APCL is higher than the average it adds the APCL
multiplied by 0.85 multiplied by 2 divided by 3 to the LMP.
40 Weeks
This method does not use the APCL, but simply counts 40 weeks, the
number of weeks in an average pregnancy from the LMP date.
Count Back
The count back method adds 7 days to the LWP and deducts 3 months, you
then have to add 1 year in the case where and your have the estimated
date of birth.
TEST DATA
I am very interested in improving this module, so if you have the
opportunity of submitting me test data it is more than welcome.
The format should be either a test file (*.t), where you choose the file
name yourself (see t/Villads.t) or you simply submit me the date of the
first day of the last period for the pregnant person, the lenght time
between periods if this varies from the avarage of 28 and possible the
result of your own/your doctor's week number calculation, then I can use
these data to validate the calculation methods used in this module.
If possible please include the information on what method your doctor is
using if this is available (SEE: METHODS).
BUGS
Please report issues via CPAN RT:
http://rt.cpan.org/NoAuth/Bugs.html?Dist=Date-Pregnancy
or by sending mail to
bug-Date-Pregnancy@rt.cpan.org
See the BUGS file for known bugs.
SEE ALSO
DateTime
Sex
Time::Clock::Biological
DISCLAIMER
The method of calculating day of birth and week numbers implemented in
this module is based on simple formulars.
The ultra sound scan is a much more accurate method and finally babies
seem to have a will of their own, so please do only use the results of
this module as a guideline, the author of this module cannot be held
responsible for the results of calculations based on use of this module.
Feedback is welcome though aswell as test data (please see TEST DATA
above).
ACKNOWLEDGEMENTS
* Thomas Eibner, who ALWAYS asks me whether I am a father by now and
acuses me of pregnant-talk (just because he cannot calculate the weeks),
now he can find out by looking at the tests included in this module or
by using this module.
* Lars Balker Rasmussen, who could not find Date-Pregnancy in his
include path "lbr can't locate Date/Pregnancy.pm in @INC" - Now he has
no excuse Date::Pregnancy is a reality.
* Lars Thegler for making me revisit the alpha version.
AUTHOR
Jonas B. Nielsen, (jonasbn) - ""
COPYRIGHT
Date-Pregnancy is (C) by Jonas B. Nielsen, (jonasbn) 2004
Date-Pregnancy is released under the artistic license
The distribution is licensed under the Artistic License, as specified by
the Artistic file in the standard perl distribution
(http://www.perl.com/language/misc/Artistic.html).