Obstetrics

• During the active phase of labor (stage two), the cervix fully dilates to allow delivery of the baby's head.
• Cesarean section involves delivering the baby through an incision made in the mother's abdomen and uterus.
• Obstetrics is a branch of medicine that deals with childbirth and the care of the mother before and after birth
• The subject matter of obstetrics includes parturition (labor), pregnancy, and puerperium in both normal and abnormal circumstances
• Pregnancy is the period before childbirth from conception/fertilization to the start of labor, with a normal duration of 280 days/40 weeks/10 lunar months
• Fertilization is the union of the sperm and the ovum
• Labor (childbirth) is the expulsion of the products of conception from the uterus when it has reached the stage of viability
• Stage of viability is at 20 weeks/500 grams/25 cm, and coming out of the fetus before 20 weeks is called abortion
• Products of conception include the fetus, placenta, and fetal sac/fetal membranes/bag of waters
• Puerperium is the postpartum period of 4 to 6 weeks when the genital organs of the mother return to their pregravid state
• Physiological Obstetrics deals with normal pregnancy, labor, and puerperium
• Gynecology deals with diseases of the nonpregnant woman
• Obstetrician is a doctor specializing in obstetrics, while a midwife is a person who attends to deliveries
• The aims of obstetrics include ensuring a healthy mother and baby, reducing maternal and infant mortality, and minimizing discomforts of pregnancy, labor, and puerperium
• Preterm Infant is born before 37 completed weeks, Postterm Infant is born after the completion of the 42nd week, and Abortus is a fetus or embryo removed from the uterus during the first half of gestation
• Direct Maternal Death includes death resulting from obstetrical complications, while Indirect Maternal Death includes maternal death not directly due to obstetrical causes
• LH stimulates interstitial cells to release testosterone
• Testosterone:

  • ABP binding of testosterone enhances spermatogenesis
  • Secondary sex characteristics
• Prostate:

  • Converts Testosterone into dihydrotestosterone (DHT) before it can bind within the nucleus
  • High levels of DHT may increase prostate size and cause male pattern baldness
• Symptoms of testosterone deficiency:

  • Increased risk of insulin resistance and DM
  • Increased visceral obesity
  • Gynecomastia: female breast development in males
  • Decreased muscle mass and bone strength
  • Sleep apnea
  • Low Libido
• Xenoestrogens:

  • Compounds found in pesticides, plastic bottles (Bisphenol A) also increase estrogen levels
• Spermatogenic stem cells of the seminiferous tubules give rise to sperm in a series of events:

  • Mitosis of spermatogonia, forming spermatocytes
  • Meiosis forms spermatids from spermatocytes
  • Spermiogenesis: spermatids form sperm
• Sperm have three major regions:

  1. Head: contains DNA and has a helmet-like acrosome containing hydrolytic enzymes that allow the sperm to penetrate and enter the egg

  2. Midpiece: contains mitochondria spiraled around the tail filaments

  3. Tail: a typical flagellum produced by a centriole
• Ovaries are the primary female reproductive organs:

  • Make female gametes (ova)
  • Secrete female sex hormones (estrogen and progesterone)
• Accessory ducts include uterine tubes, uterus, and vagina

  • Internal genitalia: ovaries and the internal ducts
  • External genitalia: external sex organs
• Perineum:

  • Space between vagina and anus
  • Lies external to the vagina and includes the mons pubis, labia, clitoris
• Vagina:

  • Thin-walled tube lying between the bladder and the rectum
  • Extending from the cervix to the exterior of the body
  • Rugae: ridges lining the vagina which allows it to stretch during intercourse and childbirth
  • Function: Provides a passageway for birth, menstrual flow, and is the organ for sexual intercourse
  • pH 4-6 due to presence of lactic acid formed by Lactobacilli Doderlein’s bacilli
• Uterus:

  • Hollow, thick-walled organ located in the pelvis anterior to the rectum and posterosuperior to the bladder
  • Body: major portion of the uterus
  • Fundus: rounded region superior to the entrance of the uterine tubes
  • Cervix: distal tip contacts the vagina
• Menstruation

  Pregnancy/gestation

  Labor
• Uterine tubes:

  • Receive the ovulated oocyte and provide a site for fertilization at the distal quarter of the tube
  • Expand distally around the ovary forming the ampulla
• Uterine Wall is composed of three layers:

  • Perimetrium: outermost serous layer; the visceral peritoneum
  • Myometrium: middle layer; interlacing layers of smooth muscle
  • Endometrium: mucosal lining of the uterine cavity changes in thickness during the menstrual cycle
• Hormonal Control of Female Reproductive Functions:

  • Hormones secreted by the hypothalamus, the anterior pituitary, and the ovaries control female reproduction and development of secondary sexual characteristics
  • Female Sex Hormones
• Luteal phase:

  • Period of corpus luteum activity (days 14-28)
  • LH transforms the ruptured follicle into a corpus luteum which produces several hormones:
  • Inhibin: inhibits further production FSH and LH
  • Progesterone and estrogen which maintain endometrium
• Implantation:

  • Blastocyst cavity
  • Inner cell mass
  • Trophoblast
• Breasts:

  • Modified sweat glands consisting of 15-25 lobes that radiate around and open at the nipple
  • Areola: pigmented skin surrounding the nipple
  • Lobes contain glandular alveoli that produce milk in lactating women
• Milk Production:

  • During pregnancy estrogen and progesterone high levels stimulate the hypothalamus to secrete prolactin-releasing hormone (PRH) which targets the anterior pituitary
  • Suckling stimulates both prolactin and oxytocin
• Heredity:

  • Transmission of genetic characteristics from parent to offspring
  • Karyotype: chart of chromosomes at metaphase
  • Body cells have 23 pairs homologous for a total of 46 chromosomes 2n (diploid number of chromosomes)
  • Sex cells (gametes) from the ova and the sperm each has 1 chromosome that determine the sex