When the critical hormone is released in high enough concentration by the mother's pituitary gland, the uterus begins periodic contractions.

oxytocin

Explanation:

Oxytocin is a hormone naturally produced by our body to generate contractions of the uterus during labor and the release of milk during breastfeeding. It was synthesized in the laboratory and thus became a very useful medication that can help save lives if correctly indicated.

This hormone can also be used to initiate labor when it does not occur naturally, and can regulate contractions when they are not effective and it is diagnosed that labor is not progressing properly.

In addition, it can also be used to contract the uterus after childbirth or abortion when bleeding is very abundant, preventing bleeding that could lead to loss of the uterus and even death if not properly controlled.

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides