Gestational dating ultrasound
The gestational age should ,therefore, be at least 10 to 12 weeks if fetal heart tone are heard. Kramer MS, Mc Lean FH, Boyd ME, Usher RH: The validity of gestational age estimation by menstrual dating in term, preterm and postterm gestations. Comparison of pregnancy dating by last menstrual period, ultrasound scanning, and their combination. Human Chorionic Gonadotropin Pregnancy Test Human chorionic gonadotropin first becomes detectable in the mother's blood and urine between 6 and 14 days after fertilization (3 to 4 weeks gestational age) [11-13]. Number 4, May 1999 (replaces educational bulletin Number 147, October 1990). Number 9, October 1999 (replaces Technical Bulletin Number 188, January 1994).
Clinical management guidelines for obstetrician-gynecologists. In addition, although a woman is most likely to become pregnant if she has sex on the day of ovulation conception may also occur from live sperm still in her reproductive tract on the day of ovulation if she had sex for up to five days before ovulation [26,27].