Chapter 6

Childbirth Stage 1

Effacement or thining of cervix.

third stage of labor

delivery of placenta

first trimester

(1-12 weeks) First trimester zygote> blastocyst Heart beat can be heard by ten weeks after last menstrual period.. Second month: spinal canal, arms, and legs form Third month: internal organs form.

Second-Trimester (13-24)

Begins with fourth month of pregnancy. Sex of fetus can be distinguished(16 weeks ultrasound or 10 weeks genetic testing) External body parts develop. Skin is covered by fine down-like hair Growth in size and feature refinement occurs. Fetal movements felt by the end of fourth month(20-22 weeks) By the trimester end, the fetus has opened its eyes.

Second Stage

Full dilation until delivery

Six Key Hormones in Pregnancy

HcG, Progesterone, Oestrogen, Prolaction, Relaxin, and Oxytocin

Progesterone

Helps establish the placenta. It stimulates growth of blood vessels that supply the womb and inhibits contraction of the uterus so it grows as the baby does. It also strengthens pelvic wall muscles for labour. If fertilazation occurs, progesterone levels will increase and start to be highest later in life followed by a drop around birth.

When does the human CNS start to form?

Neural tube starts to form at approximately two weeks old with the fluid filled cavity becoming the central canal and the four ventricles of the brain.

Oxytocin

Oxytocin levels rise at the start of labour, stimulating contractions of uterine muscle. It triggers production of prostaglandins, which increase contraction further. If labor doesn't start naturally, it can be used to induce it. Oxytocin rises sharply during childbirth and then drops after birth.

Prolactin

Prolactin is the main hormone needed to produce breast milk. It contributes to enlargement of the mammary glands and prepares them for milk production. Progesterone inhibits lactation during pregnancy. Produced by the pituitary gland. Prolactin levels tend to rise more later during pregnancy skyrocketing at the end of pregnancy.

Third-Trimester(40 weeks)

Size and strength continue to develop Down-like hair disappears Skin becomes smoother Protective, creamy, waxy substance(vernix casesosa), covers the fetus.

Placenta

a flattened circular organ in the uterus of pregnant eutherian mammals, nourishing and maintaining the fetus through the umbilical cord.

human chorionic gonadotropin (hCG) during pregnancy

hcg is produced by the placenta after implantation. It supports the function of the corpus luteum, a temporary structure in the ovaries essential in early pregnancy. It's also the hormone detected by the pregnancy test. Hcg is highest in the early weeks of pregnancy and starts to drop and plateu followed by a drop during the birth.