Antipartum Terms and Concepts

Antipartum Definitions

Key Terms

  • Gestation: Age of the fetus measured in weeks. E.g., if a fetus is 13 weeks gestated, it is at a gestation of 13 weeks.
  • Term Infants: Infants born between 37 and 42 weeks. Preterm infants are before 37 weeks, and post-term infants are beyond 42 weeks.
  • Viability: The ability for the fetus to survive outside the womb, generally considered to start at 24 weeks.

Trimesters

  • The duration of a pregnancy is divided into three trimesters:
    • First Trimester: Up to 13 weeks
    • Second Trimester: 14 to 27 weeks
    • Third Trimester: 28 weeks to delivery

Stages of Pregnancy

  • Antepartum: The period before labor. Example: A patient hospitalized for nearly 100 days with twins is considered antepartum.
  • Intrapartum: The period during labor.
  • Postpartum: The period after delivery, typically considered to be about six weeks, but may vary based on clinical scenarios.

Clinical Insights

  • Post-term infants typically face more health challenges compared to preterm infants. For instance, placental deterioration post-39 weeks can severely impact the infant's health.
  • Viability is often misunderstood; achieving viability at 24 weeks does not guarantee good outcomes, as the risk of severe disabilities increases.

Pregnancy Metrics

Gravida and Para System

  • Gravida (G): Total number of pregnancies, including miscarriages.
  • Para (P): Number of viable pregnancies (greater than 20 weeks).
    • Example: A woman with two live births and three miscarriages is G5, P2.

Medication Classifications

  • Tocolytics: Used to stop uterine contractions. Examples include:
    • Terbutaline: A subcutaneous medication used for tachysystole (increased contractions).
    • Nifedipine: A blood pressure medication that relaxes smooth muscle and slows contractions.

Pregnancy and Labor Medications

Steroids

  • Administered to promote fetal lung development in anticipated premature deliveries. Given as intramuscular injections, ideally 24 hours apart.

Uterotonics

  • Oxytocin: Induces labor contractions.
  • Methergine and Hemobate: Used for postpartum hemorrhage management; contraindicated in patients with hypertension or asthma respectively.

Signs of Pregnancy

Subjective Signs (Presumptive)

  • Missed periods, breast tenderness, fatigue, nausea.

Objective Signs (Probable)

  • Goodell's sign (cervical softening), Chadwick's sign (cyanosis of the cervix), and pregnancy tests.

Positive Signs

  • Detection of fetal heartbeat or ultrasound imaging of the fetus.

Hormones in Pregnancy

  • HCG: Maintains the corpus luteum; detectable in urine 10-14 days after conception.
  • Estrogen: Promotes blood flow to the uterus and prepares breast tissue for lactation.
  • Progesterone: Maintains pregnancy and conditions uterine muscles for childbirth.

Conclusion

  • Understanding the terms and processes surrounding pregnancy is vital, particularly for accurate assessment and care in antepartum, intrapartum, and postpartum contexts. Knowledge of medication effects, signs of pregnancy, and physiological changes is critical for healthcare providers.