In 2006, the number of live births in the U.S. totaled
nearly 4.3 million, the largest number since 1961. The percentage
of women who received prenatal care in the first trimester decreased
and the percentage of women with late or no prenatal care increased
in 2006.1 These trends are concerning,
as ongoing prenatal care is associated with improved pregnancy outcomes.
Recent attention is focusing on improving women’s health
before conception, in addition to prenatal care, to improve pregnancy
outcomes. Many of the medical conditions, environmental exposures,
personal behaviors, and psychosocial risks that are associated with negative
pregnancy outcomes can be identified and modified or eliminated
Regardless of the chief complaint, the possibility of pregnancy must
be considered in every woman of reproductive age who presents to
the ED. The use of barrier methods, contraceptives, or even sterilization does
not guarantee pregnancy prevention. Unintended pregnancies occur
because of lack of contraception, imperfect use of contraception,
and contraceptive failure. Forty eight percent of unintended pregnancies
occur in a month during contraception.3 The failure
rates of barrier methods are variable. Although the failure rate
with compliant use of oral contraceptives is <1 per 100, nearly
30% of women who rely solely on oral contraceptives to
prevent pregnancy are not consistently compliant.4 During
the first 5 years of therapy with levonorgestrel implants, the annual
pregnancy rate is 0.8 per 100. The failure rate of implants increases
with time.5 Tubal sterilization is a more reliable
means of pregnancy prevention, with the failure rate depending on
the surgical technique. Partial salpingectomy has a failure rate
of only 0.75%.6
Gravidity denotes the total number of pregnancies
regardless of duration and outcome. Parity denotes
the number of pregnancies completed to delivery during the viable
period. Parity is not increased for a pregnancy resulting in multiple
births or decreased for a stillborn fetus. Notation of obstetric
history typically lists the gravidity (G) followed by the appropriate
number and then the parity (P) followed by the appropriate number.
After the gravidity and parity, there may be a listing of the number
of term deliveries, preterm deliveries, abortions, and living children.
The latter four numbers are separated by hyphens and listed in parentheses.
For example, the obstetric history of a woman during her seventh
pregnancy who has had four term deliveries, one preterm delivery,
and one abortion and has five living children is abbreviated G7
The duration of pregnancy is approximately 40 weeks. By convention,
gestational age (or menstrual age) is calculated from the first
day of the last normal menstrual period. Ovulation normally occurs
around day 14 of the menstrual cycle. After ovulation, the ovocyte
remains capable of being successfully fertilized for up to 12 hours. Fertilization usually
takes place in the ampulla of the oviduct. The fertilized ovocyte
(zygote) transforms into the morula as it travels toward the uterus.
By 6 days after fertilization, it enters the ...