How is gestational age determined prior to tocolytic therapy in preterm labor?

Updated: Dec 17, 2018
  • Author: Michael G Ross, MD, MPH; Chief Editor: Carl V Smith, MD  more...
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Answer

Answer

One should always attempt to determine gestational age by first identifying the first day of the last menstrual period (LMP) and confirming it by one or more of the following:

  • Positive pregnancy test (home or clinic) prior to the expected date of the second missed period

  • Uterine size determined by bimanual examination prior to 12 weeks' gestation

  • Doppler fetal heart tones noted prior to 12 weeks' gestation

  • Ultrasonographic estimation of gestational age (ie, first trimester within 1 wk, second trimester within 2 wk, and third trimester within 3 wk)


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