Our Gemara on Amud Aleph tells us that an infant born with a lot of hair may cut it on Chol HaMoed. This is because it is analogous to the person released from prison who also is allowed to get a haircut since he had no ability to do so before Yom Tov. The Gemara rhetorically asks, who could be more imprisoned than a child in the womb? That is, of course he is not free to get a haircut in utero.

This Gemara provides a peshat for a difficult to understand Tur (OH 114) who interprets the Second beracha of Shemoneh Esre, based on a Gemara (Ta’anis 2a-b) that tells us there are four fundamental powers that Hashem holds the keys to, and does not delegate to emissaries: Rain, Birthing, Resurrection of the Dead and the blessings of sustenance and livelihood. The second beracha of Shemoneh Esre, known as “Gevuros” refers to these essential powers:

Mashiv Haruach is obviously referring to the rain. Mechalkel Chayyim Bechessed is obviously referring to Sustenance and livelihood, while Mechaye Mesim is clearly the resurrection of the dead. But where do we find a reference to birthing in the blessing?

The Perisha (Op. Cit.) uses our Gemara as a proof that birthing is similar to being released from prison, thus matir asurim is what the Tur meant when he said that this blessing referred to birthing.

Well we now have one more segulah for easy labor aside from pesicha of the aron kodesh, and that is have kavannah during the second beracha of shemoneh esre.