Lecture 4: Pregnancy, Delivery, & Birth control: study guide

Ovum Transport

Ovum is released from the ovary & moves to the fallopian tube via cilia & peristalsis

Sperm Transport

Sperm move through the female tract, undergoing capitation to enable fertilization

• Estrogen is excreted in abundance to prepare the female reproductive tract for efficient sperm transport by stimulating watery secretion from cervical cell lining, allowing sperm to pass through the canal

Fertilization

• Acrosomal Reaction: Enzyme released by sperm allow penetration fo the zona pellucida

• Block to polyspermy prevents multiple sperm from entering the egg

Early development

• Zygote undergoes mitosis division to form a morula → blastocyst

• Implantation: Blastocyte embeds into the endometrium

  • ~6-7 days post-fertilization

Anatomy and Functions of the Placenta:

Chorion & chorionic Viki facilitate maternal-fetal exchange of oxygen, nutrients, & waste

Umbilical artery and vein

• Reverse

  • Artery transports fetal waste & low O2 blood to placenta

  • Vein transports nutrient & O2-rich blood from the placenta to the fetus

Endocrine function produces hormones: hCG

Maintains the corpus luteum & early pregnancy

Endocrine function produces hormones: Progesterone & Estrogen

Support uterine lining & prevent uterine contractions

Endocrine function produces hormones: hPL

Alters maternal metabolism to support fetal growth

Maternal hormone blockade

Isolates fetal metabolism from direct maternal hormonal influence

• Insulin: Does NOT cross the placenta

  • Fetal metabolism is regulated by insulin secreted by the fetal pancreas in response to maternal glucose levels

• Counter-Regulatory Hormones:

  • Glucagon, cortisol, GH

  • Do NOT cross placenta

“Immune Privilege”

Placenta creates a barrier preventing maternal immune cells from targeting the fetus as “foreign” tissue

Drug Transport

Placenta traffics substances that pose risks to fetal development

• Pharmaceuticals, illicit substances (e.g, cocaine, methamphetamine), & legal substances (alcohol, tobacco, opioids)

Hormonal and Physiological Preparation for Labor: Cervical Ripening

Prostaglandins soften the cervix

Hormonal and Physiological Preparation for Labor: Uterine Contractions

• Positive (+) feedback loop

  • Oxytocin stimulates contraction => increase prostaglandin release

• Prostaglandins + oxytocin coordinate stronger contractions

Hormonal and Physiological Preparation for Labor: Stages of Labor

1. Cervical dilation

2. Delivery of fetus

3. Placental delivery

Regulation of Lactation: Prolactin

Stimulates milk production

Regulation of Lactation: Oxytocin

Triggers milk ejection (letdown reflex)

Regulation of Lactation: Feedback

Suckling stimulated prolactin + Oxytocin release

Methods of Birth Control: Barrier methods

Present sperm-egg contact

• ex: Condoms, diaphragms

Methods of Birth Control: Hormonal methods: Combined oral contraceptive (COCs)

Prevent ovulation by suppressing LH & FSH

Methods of Birth Control: Hormonal methods: Sustained release formulations

• Vaginal ring (NuvaRing)

• “Patch”

Methods of Birth Control: Hormonal methods: Progesterone-only

Thicken cervical mucus, thin the endometrium

Methods of Birth Control: Emergency Contraception

RU486 blocks progesterone receptors => preventing implantation

Capacitation

Sperm activation in the female tract

Zona Pellucida

Glycoprotein layer where sper bind & penetrate the oocyte

hCG

• Maintains corpus luteum

• Support early pregnancy

Oxytocin

• Stimulates uterine contractions (Oxytocin + Prostaglandin)

• Milk ejection (Oxytocin + Prolactin)

Prostaglandins

Promote:

• cervical ripening

• Uterine contractions

RU486

Progesterone antagonist used in emergency contraception

Clinical: Preeclampsia

• High BP & Proteinuria (abnormal amounts of protein in the urine) due to placental dysfunction

• Complications: Eclampsia, preterm birth

Clinical: Placental Insufficiency

Inadequate nutrient/O2 delivery → Fetal Growth Restriction (FGR)

Clinical: Substance Exposure

• Fetal Alcohol Syndrome: due to alcohol crossing the placenta => growth retardation, cognitive deficients, & facial anomalies

• Neonatal Abstinence Syndrome (NAS): withdraw symptoms in newborns exposed to opioids during preganancy

Clinical: Maternal Obesity & Lactation

Delayed lactogenesis due to reduced prolactin sensitivity