Pregnancy, Labor, and Delivery

1. Pregnancy, Labor, and Delivery Calla Holmgren, MD Department of Obstetrics & Gynecology University of Washington

2. Objectives • Review normal physiologic changes in pregnancy • Discuss historical context of labor and delivery • Review normal and abnormal labor • Evaluate interventions for abnormal labor

3. Cardiovascular Changes •  Major hemodynamic changes induced by pregnancy include • Increase in cardiac output • Sodium and water retention leading to blood volume expansion • Increase until 34 weeks gestation • Reductions in systemic vascular resistance and systemic blood pressure

4. Cardiovascular Changes • These changes begin early in pregnancy • Reach their peak during the second trimester, and then remain relatively constant until delivery • They contribute to optimal growth and development of the fetus • Help to protect the mother from the risks of delivery, such as hemorrhage

5. Hemodynamic changes in normal pregnancy

6. Pulmonary Changes • Marked changes in respiratory system during pregnancy • These can be measured using direct spirometry • Vital Capacity- increased by 100-200 mL • Inspiratory Capacity- increased by 300 mL • Expiratory Reserve Volume- decreases • Residual Volume- Decreases • Functional Residual Capacity- reduced • Tidal Volume- increases from 500 to 700 mL • Minute Ventilation- increases 40%

7. Pulmonary Changes • The total of these changes is increased ventilation • Due to deeper but not more frequent breathing • Most likely used to help supply increased basal oxygen consumption

8. Gastrointestinal Changes • Pregnancy has little, if any, effect on gastrointestinal secretion or absorption • But it has a major effect on gastrointestinal motility • Hormones • Enlarging uterus

9. Endocrine Changes • Endocrine adaptations to the pregnant state begin just after conception and evolve through delivery • They almost completely revert back to the nonpregnant state over a period of weeks • Virtually all endocrine glands are affected

10. Endocrine Changes • Maternal endocrine adaptations to pregnancy • Hypothalamus • Pituitary • Parathyroid • Thyroid • Adrenal glands • Ovary

11. Musculoskeletal Changes • Anatomic and physiologic changes occurring during pregnancy have the potential to affect the musculoskeletal system at rest and during exercise • Weight gain • Shift in center of gravity • Increased ligamentous laxity

12. Musculoskeletal Changes • Weight gain • Typically 11.5 to 16 kg • May double the forces across joints compared to nonpregnant forces • Shift in center of gravity • Shifted forward • A posture of increased lumbar lordosis • Back pain • Loss of balance; increased fall risk • Increased ligamentous laxity • Related to the effects of estrogen and relaxin

13. Prenatal Care • The major goal of prenatal care is to ensure the birth of a healthy baby with minimal risk for the mother • Early, accurate estimation of gestational age • Identification of the patient at risk for complications • Ongoing evaluation of the health status of both mother and fetus • Anticipation of problems and intervention, if possible, to prevent or minimize morbidity • Patient education and communication

14. Prenatal Care • History and physical • Laboratory tests • Ultrasound examination • Patient education • Preparation for labor and delivery

15. History and Physical • History • Personal and demographic information • Past obstetrical history • Personal and family medical history • Past surgical history • Genetic history • Menstrual and gynecological history • Current pregnancy history • Psychosocial information • Physical • Special attention to uterine size and shape and evaluation of the adnexa • Fetal heart tones • Doppler: 9 to 12 weeks of gestation • Transvaginal ultrasound 5.5 to 6.0 weeks

16. Laboratory Assessment • Hematocrit or hemoglobin to detect anemia • Cervical cytology • Blood type and screen • Rubella immunity testing • Urinary infection testing • Syphilis testing • Hepatitis B antigen testing • Gonorrhea and Chlamydia testing • HIV testing • Thyroid disorders? • Heritable disorders • Genetic screening

17. Ultrasound Examination • First trimester • Accurately dates pregnancy • Assessment of fetal well being • 18-20 weeks • Anatomic survey • Late second/third trimester • Growth • Fetal well being

18. Patient Education • Seat belts • Vitamins, nutrition, and weight gain • Substance use  • Infection precautions • Work  • Exercise  • Birth defects and genetic issues • Use of medications • Airline travel

19. The History of Childbirth • Historically, pregnancy has been managed by women (family, friends, midwife) with delivery in the home • In the 14th-18th Centuries medicine was dominated by men and the Church

20. History of Childbirth • Industrialization of America brought mothers from their homes to hospitals (“lying-in”) for birth • Obstetrics was then performed by surgeons (not midwives)

21. Why do we need to know about labor? • Four million births per year in the United States alone • In underdeveloped nations – lack of skilled attendants • Natural process with modernization

22. Maternal Mortality Ratio (WHO, 2002)

23. Maternal Mortality(Grady Memorial Hospital, GA)

24. Maternal Mortality(GMH, 1949-2000)

25. What is labor? • Labor = the act of uterine contractions combined with cervical change • Fetus is gradually pushed through the birth canal (consisting of the cervix, vagina and perineum) • Placenta is extruded and uterus involutes

26. What is labor?

27. What is labor?

28. What starts labor? • An intricate and baffling association between fetus and mother exist • Several components are known, but many are not – extrapolated from animals • Involves hormonal communications between mother and fetus • In other words – we can speculate but we’re not quite sure!

29. Induction of Labor • Need to have a reason! • Maternal indications • Fetal indications • Need to have a plan! • Favorable cervix? • No? Cervical ripening • Yes? Pitocin

30. Bishop Score

31. Cervical Ripening • Mechanical • Stripping (or sweeping) of the fetal membranes • Placement of hygroscopic dilators within the endocervical canal • Insertion of a balloon catheter above the internal cervical os (with or without infusion of extra-amniotic saline) • Pharmacologic • Prostaglandins • Prostaglandin E2-cervidil • Prostaglandin E1-misoprostil

32. After the initiation of labor… • Factors responsible for the ongoing labor process include: • Oxytocin • Prostaglandins (PGF2-alpha, thromboxane, PGE1,E3) • Endothelin (by receptor-PLC coupling via nifedipine sensitive channels) • Epidermal Growth Factor

33. How does the uterus contract? • The uterus is made from a weave of smooth muscle (myometrium) covered by a smooth cellular surface (serosa) – all formed by the joining of the two original mullerian horns • The cavity is hollow and lined by vascular/stromal bed that is responsive to hormonal stimulation (i.e. menstrual cycle)

34. Structure of the uterus

35. What does the myometrium need to contract? • CALCIUM! • Calcium channels allow influx which through a cascade of events activates myosin • Smaller calcium supply comes from other organelles (i.e.. Sarcoplasmic reticulum) • These all play a part in how we can manipulate labor!

36. The Cardinal Movements of Labor

37. Stages of Labor • First stage – Latent and active labor • Second stage – Descent with pushing to delivery of baby • Third stage – Delivery of placenta • Fourth stage – involution of the uterus

38. Stages of Labor

39. Stages of Labor • Stage 1 (Latent Phase) • Uterus and cervix prepare for active labor • Dilatation up to 4 cm • Variable length of time

40. Stages of Labor • Stage 1 • The “Active” Phase – rapid cervical dilatation from 4 centimeters to 10 centimeters (or complete dilatation). Varies for nulliparous vs. multiparous patients • Nulliparous – 1.2 cm/hr • Multiparous – 1.5 cm/hr

41. Stages of Labor • Stage 2 “Pushing” • Starts from complete dilatation to delivery of the fetus • Variable depending on parity maternal forces • Fetus has to make it’s way through the curves of the pelvis

42. Third Stage of Labor • Stage 3 • From delivery of the fetus to delivery of the placenta • Variable amounts of time for placental extrusion but generally within the first 20-30 minutes • Medications can be used to augment placenta delivery and post-partum bleeding

43. Fourth Stage of Labor • Stage 4 • Immediate period after placental delivery • Uterus contracts to close off venous sinuses and slow bleeding • Watch for signs of post-partum hemorrhage

44. When is labor not progressing?

45. Fetal causes of dystocia • Breech – presenting parts not optimal • Macrosomia – too big! • Occiput posterior – fetus is facing “sunnyside up” (face up) • Malpresentation – fetal head is not perfectly flexed • Compound presentation – two parts presenting • Congenital abnormalities obstructed in the birth canal

46. Breech Presentation • Non-vertex presenting part – Buttocks! • Occurs in about 3-5% of term deliveries • Forms of breech presentation include complete, footling, and frank breech

47. Breech presentation • Look for possible causes (large baby, no fluid, birth defects, uterine anomalies) • Risks of labor from breech presentations include fetal injury, cord prolapse, entrapment, maternal injury • Delivery options include vaginal breech delivery, external cephalic version (ECV), elective cesarean section

48. Occiput posterior (OP) presentation • Approximately 10% of deliveries • Face is looking up towards the ceiling versus the floor • Fetus must perform opposite flexion/extension maneuvers to navigate the birth canal

49. OP Presentations • What can we do about OP presentations? • Leave it alone – babies can deliver from OP, ROP and LOP presentations (back labor!) • Rotate the fetal head – manually or with forceps • Change labor positions for the mother such as knee-chest • Offer regional anesthesia – allows for pelvic muscle relaxation • If labor arrests - cesarean

50. Malpresentation • Occurs when the bony parietal bones of the fetus are not the presenting. These include: • Face presentation 0.1-0.2% of all deliveries (head is hyper-extended) • Let nature work its magic – they usually deliver vaginally • Do not try to correct • Babies can have edematous faces, they resolve