From the Daily Beast:

…Life starts earliest in Arizona, which now defines gestational age as beginning on the first day of a woman’s last period, rather than at fertilization…

I am without words.

=======
UPDATE
=======

From the comments:

When the medical profession defines gestation as beginning on the first day of the woman’s last period they extend the pregnancy to include an additional two weeks. Pregnancy is then defined as being 42 weeks long. But it was never intended to be used as a legal term.

Using gestational age to interpret feotal development age muddies the waters and sets a precedent for personhood lobbyists to shorten the currently legally accepted timeframes for early abortion. Once that precedent is set, the timing on heretofore legally obtained abortions is reduced by two to four weeks and we will be vulnerable to being charged with accountability of a feotus that hasn’t even been conceived yet.

Gestational age is a medical term which should never be interjected onto actual feotal development. It is complete overkill. If it is allowed to be used as a legal definition for ‘beginning of life’  our rights as women will be in serious jeopardy.

From John Hopkins online:

Nowhere in the language used in the Arizona legislation does the author adjust the additional days added at the begi9nning of a 42 week gestational period. Instead, the 20 week legal precedent used to define legal abortions has been truncated by two full weeks, cutting the time to obtain a legal abortion from 20 down to 18 weeks. And this doesn’t even take into account the timing of late ovulation which could then tack an additional one to two weeks onto the time between ‘the first day of a woman’s last period’ and the time of actual conception.

It should be important to note that no matter how gestational age is defined, the science behind the actual length of a pregnancy is not altered. It still takes 38 to 40 weeks to incubate a healthy feotus, ready to emerge and take it’s first breath no matter where you decide to place the start marker. Legislating this marker is then redundant, and only useful if the intent is to create new precedent by which lobbyists can alter existing laws.

Gestational age is a ‘method of measurement’ not a legal term but we run the risk of it becoming a legal fact and overturning the medical science used to create our abortion laws, and laws making women liable during feotal development.

It’s also one dangerous step towards making personhood effective a full month prior to a child even being conceived. Gestational age and feotal development after conception are not the same. It’s inaccurate to interpose the terms and then create legislation based upon the inaccuracies.

Thank you kitchem for your thoughtful comment.

Ok that’s my two cents folks – your thoughts?