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Source: Ward KE, O’Brien BM. Pregnancy and Lactation: Therapeutic Considerations. In: DiPiro JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM, eds. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. http://accesspharmacy.com/content.aspx?aid=7992979. Accessed June 8, 2012.

  • Therapeutic issues affecting both mother and child, from planning for pregnancy through birth.

  • Delayed gastric emptying and vomiting may alter drug absorption during pregnancy.
  • Increased gastric pH may affect absorption of weak acids and bases.
  • Higher estrogen and progesterone levels may alter liver enzyme activity and increase elimination of some drugs but accumulation of others.
  • Maternal plasma volume, cardiac output, and glomerular filtration increase by 30–50% during pregnancy, possibly lowering plasma concentration of renally cleared drugs.
  • Increased body fat may increase volume of distribution of fat-soluble drugs.
  • Reduced plasma albumin concentrations may increase volume of distribution of highly protein-bound drugs; however, unbound drugs more rapidly cleared by liver and kidneys.
  • Placenta is organ of exchange between mother and fetus for a number of substances, including drugs.
  • Drug molecular weights affect drug transfer across placenta:
    • Molecular weights >500 daltons (D) cross readily.
    • Molecular weights from 600–1000 D cross more slowly.
    • Molecular weights >1000 D (e.g., insulin and heparin) do not cross in significant amounts.
  • Lipophilic drugs (e.g., opiates and antibiotics) cross placenta more easily than water-soluble drugs.

Signs and Symptoms

  • Pregnancy-influenced issues
    • Common during pregnancy:
    • Hyperemesis gravidarum (severe nausea/vomiting causing weight loss >5% of prepregnancy weight and ketonuria) occurs in 1–3% of pregnant women.
    • Gestational diabetes mellitus (GDM) more common in African Americans, Native Americans, Asian Americans, Hispanic Americans, and Pacific Islanders.
    • Hypertension, including:
      • Gestational hypertension: Pregnancy-induced hypertension without proteinuria
      • Preeclampsia: Hypertension with proteinuria
      • Eclampsia: Preeclampsia with seizures (medical emergency)
      • Chronic hypertension: Diagnosed prior to pregnancy with or without overlying preeclampsia
    • Venous thromboembolism (VTE), with risk factors in pregnancy of:
      • Increasing age
      • History of thromboembolism
      • Hypercoagulable conditions
      • Operative vaginal delivery or cesarean section
      • Obesity
      • Family history of thrombosis
  • Acute care issues that may arise in pregnancy
    • Headache
    • Urinary tract infections
    • Sexually transmitted infections (STIs)
  • Chronic illnesses that may occur in pregnancy
  • Labor and delivery
    • Preterm labor
    • Group B Streptococcus infection
    • Cervical ripening and labor induction
    • Labor analgesia

  • Refer to individual disorders for diagnostic considerations.

  • Provide preconception interventions to help ensure optimal pregnancy outcomes.
  • Relieve symptoms associated with pregnancy-influenced medical disorders.
  • Prevent congenital malformations caused by medication exposure.
  • Goals for GDM:
    • Fasting plasma glucose <90–99 mg/dL (5–5.5 mmol/L)
    • 1-hour postprandial plasma glucose concentrations 140 mg/dL (7.8 mmol/L) or less
    • 2-hour postprandial glucose <120–127 mg/dL (6.7–7 mmol/L)

  • Principles for selecting medications during pregnancy:
    • Select drugs used safely for long periods.
    • Prescribe doses at lower end of recommended range.
    • Eliminate nonessential medication and discourage self-medication.
    • Avoid medications known to be harmful.

  • Encourage folic acid intake (400 mcg/day) by all women of childbearing potential to reduce risk for neural tube defects in offspring.
  • Avoiding alcohol, tobacco, and other substances prior to pregnancy improves outcomes.
  • For constipation during pregnancy, before drug therapy attempt:
    • Education
    • Physical exercise
    • Biofeedback
    • Increased dietary fiber ...

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