Normal acetylcholine and receptors. Nicotine affects the neurotransmitter acetylcholine and its receptor. This receptor is located in many brain structures and body organs. It carries messages related to respiration, heart rate, memory, alertness, and muscle movement.
Around the middle of the second trimester, movement of the fetus may be felt. At 28 weeks, more than 90% of babies can survive outside of the uterus if provided high-quality medical care. The third trimester is from 29 weeks through 40 weeks.
Definitions for third trimester. Here are all the possible meanings and translations of the word third trimester. Princeton's WordNet(0.00 / 0 votes)Rate this definition: third trimester(noun) time period extending from the 28th week of gestation until delivery.