Thankfully this petition was a spoof because the college students weren't. Yes, the words "fourth trimester" can either imply infanticide or a complete lack of command of the English language (the "tri" part of the word means "three" so a "fourth trimester" would be nonsensical).
At any rate, these people sign it either intending to promote infanticide or simply not understanding the meaning of the words "fourth trimester". Such are the less-than-impressive results of Dewey-inspired progressive brainwashing. These young people have been transformed into sheeple; and this is by design of the disciples of Dewey and his humanist cabal.
If you look closely, you can see the banners in the background identifying this campus as being on George Mason University in Fairfax VA.