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Labor, Delivery, and Changes at Birth. Fred Hill, MA, RRT. Fetus in Uterus. Fetus in Uterus. Events of Birth (Maternal). Rupture of membranes Dilation of cervix Contraction of uterus Separation of the placenta Shrinking of the uterus. Stages of Labor & Delivery.
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Labor, Delivery, and Changes at Birth Fred Hill, MA, RRT
Events of Birth (Maternal) • Rupture of membranes • Dilation of cervix • Contraction of uterus • Separation of the placenta • Shrinking of the uterus
Stages of Labor & Delivery • Stage I: Onset of regular contractions to full dilation and effacement of the cervix • Primigravida: 16 – 18 hours • Multigravida: 7 – 12 hours • Stage II: Full dilation (10 cm) and effacement of the cervix to delivery of the baby • Primigravida: 1 – 2 hours • Multigravida: 20 mins • Stage III: Delivery of the baby to delivery of the placenta • Primigravida: 3 – 4 mins • Multigravida: 4 – 5 mins
Tocolysis • Beta-2 sympathomimetics • Terbutaline sulfate • Ritodrine hydrocholoride • Magnesium sulfate • Indomethacin • Calcium channel blockers
Dystocia • Uterine dysfunction • Abnormal fetal presentation • Cephalopelvic dysproportion • Hydrocephalus • Excessive fetal size (maternal diabetes) • Small pelvic dimensions • Abnormality in shape of birth canal
Abnormal Fetal Presentation • Normal presentation: Vertex ( head first), 95% • Abnormal presentation • Cephalic • Breech (buttocks down) • Face • Brow • Shoulder • Transverse lie
Other Problems • Prolapse of umbilical cord • Cord wrapping around fetus • Placental abnormalities • Placenta previa: Implantation in lower uterus • Abruptio placentae
Other Risky Deliveries • Cesarean deliveries • Multiple gestations
Changes at Birth • Vaginal squeeze when head presents • Presentation of chest and recoil of chest • First breath: high initial pressures (-100 cm H2O) • Succeeding breaths require less negative pressure • Remaining liquid in lungs • Expelled by coughing and sneezing • Absorption into lung interstitium into lynphatics
Fetal to Adult Circulation • Major changes • First and subsequent breaths • Reduces pulmonary vascular resistance • Air replaces liquid surrounding vasculature • ↑ PaO2 → pulmonary vasodilation • Increase in systemic vascular resistance • Clamping of umbilical cord • R → L Shunting changes to L → R • Foramen ovale closes: mechanical • Ductusarteriosus begins to close due to chemical changes • Cessation of blood flow leads to constriction of: • Ductusvenosus • Umbilical arteries and veins