Pregnancy and Prenatal Care

• Pregnancy


  The state of having products of conception implanted normally or abnormally in the uterus or occasionally elsewhere. It is terminated by spontaneous or elective abortion or by delivery.
• A myriad of physiologic changes occur in a pregnant woman, which affect every organ system.
• Diagnosis of pregnancy


  In a patient who has regular menstrual cycles and is sexually active, a period delayed by more than a few days to a week is suggestive of pregnancy. Even at this early stage, patients may exhibit signs and symptoms of pregnancy.
• Signs of pregnancy


  • Bluish discoloration of vagina and cervix (Chadwick sign)
  • Softening and cyanosis of the cervix at or after 4 wk (Goodell sign)
  • Softening of the uterus after 6 wk (Ladin sign)
  • Breast swelling and tenderness
  • Development of the linea nigra from umbilicus to pubis
  • Telangiectasias
  • Palmar erythema
• Symptoms of pregnancy


  • Amenorrhea
  • Nausea and vomiting
  • Breast pain
  • Quickening-fetal movement
• Urine pregnancy tests


  Over-the-counter (OTC) urine pregnancy tests have a high sensitivity and will be positive around the time of the missed menstrual cycle. These urine tests and the hospital laboratory serum assays test for the beta subunit of human chorionic gonadotropin (ẞ-hCG).
• ẞ-hCG


  This hormone produced by the placenta will rise to a peak of 100,000 mIU/mL by 10 weeks of gestation, decrease throughout the second trimester, and then level off at approximately 20,000 to 30,000 mIU/mL in the third trimester.
• Ultrasound confirmation of pregnancy


  A viable pregnancy can be confirmed by ultrasound, which may show the gestational sac as early as 5 weeks on a transvaginal ultrasound or at a ẞ-hCG of 1,500 to 2,000 mIU/mL. Fetal heart motion may be seen on transvaginal ultrasound as soon as 6 weeks or at a ẞ-hCG of 5,000 to 6,000 mIU/mL.
• Embryo


  The conceptus from the time of fertilization until the pregnancy is 8 weeks along (10 weeks' gestational age [GA])
• Fetus


  The conceptus after 8 weeks until the time of birth
• Infant


  The period between delivery and 1 year of age
• Trimesters of pregnancy


  First trimester lasts until 12 weeks but is also defined as up to 14 weeks' GA, the second trimester lasts from 12 to 14 until 24 to 28 weeks' GA, and the third trimester lasts from 24 to 28 weeks until delivery.
• Previable


  Infant delivered prior to 24 weeks
• Preterm


  Infant delivered between 24 and 37 weeks
• Term


  Infant delivered between 37 and 42 weeks
• Postterm


  Pregnancy carried beyond 42 weeks
• Gravidity (G)


  The number of times a woman has been pregnant
• Parity (P)


  The number of pregnancies that led to a birth at or beyond 20 weeks' GA or of an infant weighing more than 500 g
• TPAL designation


  A more specific designation of pregnancy outcomes that divides parity into term and preterm deliveries and also adds the number of abortuses and the number of living children.
• Abortuses


  All pregnancy losses prior to 20 weeks, both therapeutic and spontaneous, as well as ectopic pregnancies
• Nulligravid, primigravid, multigravid


  Having 0, 1, or more than 1 previous pregnancies, respectively
• Nulliparous, primiparous, multiparous


  Having 0, 1, or more than 1 previous births at or beyond 20 weeks' GA or of an infant weighing more than 500 g, respectively
• Grand multip


  A woman whose parity is greater than or equal to 5
• Gestational age (GA)


  The age in weeks and days measured from the last menstrual period (LMP)
• Developmental age (DA)


  The number of weeks and days since fertilization
• Estimated date of confinement (EDC) or estimated date of delivery (EDD)


  Calculated by subtracting 3 months from the LMP and adding 7 days
• If the date of ovulation is known, as in assisted reproductive technology (ART), the EDC can be calculated by adding 266 days.
• Pregnancy dating can be confirmed and should be consistent with the examination of the uterine size at the first prenatal appointment.
• Ultrasound has a level of uncertainty that increases during the pregnancy, but it is rarely off by more than 7% to 8% at any GA.
• Ultrasound dating of pregnancy decreases in accuracy as the pregnancy progresses, so determining and confirming pregnancy dating at the first interaction between a pregnant woman and the health care system is imperative.
• Approximately 5% to 15% of women may be oligo-ovulatory, meaning they ovulate beyond the usual 14th day of the cycle. Thus, their LMP dating may overdiagnose a prolonged (≥41 weeks' gestation) or postterm pregnancy (≥42 weeks' gestation).
• Cardiovascular changes in pregnancy


  • Cardiac output increases by 30% to 50%, with most increases occurring during the first trimester and reaching a maximum between 20 and 24 weeks' gestation
  • Systemic vascular resistance decreases, resulting in a fall in arterial blood pressure
• Pulmonary changes in pregnancy

  • Tidal volume increases by 30% to 40%, despite a 5% decrease in total lung capacity
  • Minute ventilation increases by 30% to 40%, leading to an increase in alveolar (PAO2) and arterial (PaO2) PO2 levels and a decrease in PACO2 and PaCO2 levels
• Dyspnea of pregnancy


  Occurs in 60% to 70% of patients, possibly secondary to decreased PaCO2 levels, increased VT, or decreased TLC
• Gastrointestinal changes in pregnancy

  • Nausea and vomiting occur in more than 70% of pregnancies, typically resolving by 14 to 16 weeks' gestation
  • Stomach has prolonged gastric emptying times and the gastroesophageal sphincter has decreased tone, leading to reflux and ptyalism
  • Large bowel has decreased motility, leading to increased water absorption and constipation
• Hyperemesis gravidarum


  Severe form of morning sickness associated with weight loss (≥5% of prepregnancy weight) and ketosis
• Renal changes in pregnancy

  • Kidneys increase in size and the ureters dilate, which may lead to increased rates of pyelonephritis
  • Glomerular filtration rate increases by 50% early in pregnancy and is maintained until delivery
• Hematologic changes in pregnancy

  • Plasma volume increases by 50%, but the RBC volume increases by only 20% to 30%, leading to a decrease in the hematocrit (dilutional anemia)
  • WBC count increases to a mean of 10.5 million/mL with a range of 6 to 16 million
  • Slight decrease in platelet concentration, with 7% to 8% of patients having a platelet count between 100 and 150 million/mL
  • Considered a hypercoagulable state with an increase in thromboembolic events
• Endocrine changes in pregnancy

  • Hyperestrogenic state, with estrogen primarily produced by the placenta
  • hCG levels double approximately every 48 hours during early pregnancy, reaching a peak at 10 to 12 weeks and then declining
  • Progesterone levels increase over the course of pregnancy, causing relaxation of smooth muscle
  • hPL is produced in the placenta and has a diabetogenic effect
  • Prolactin levels are markedly increased during pregnancy
• Musculoskeletal and dermatologic changes in pregnancy

  • Shift in posture and lower back strain, worsening throughout pregnancy
  • Numerous skin changes including spider angiomata, palmar erythema, and hyperpigmentation