The estimated date of delivery, or EDD, represents a calculation based on 280 days (or 9 months and 7 days) from the onset of the last menstrual period (LMP), the approach used by most pregnancy wheels, or 266 days from the date of conception. Typically, ovulation is assumed to be approximately 14 days before the next 28-day menstrual cycle.³ NOTE: You may also see the abbreviation last normal menstrual period (LNMP) is used.

Reliable criteria for accurately dating a pregnancy can be obtained in several ways. When assisted methods to achieve pregnancy are used, such as intrauterine insemination or embryo transfer, the conception/fertilization date is certain; therefore, that date should be used to calculate the EDD. Using an early first trimester ultrasound can facilitate obtaining an accurate EDD. Though the gestational sac is the first sonographic sign of an intrauterine pregnancy at 4.5 to 5 weeks, the crown-rump length (CRL) becomes visible at 5 to 10 weeks and is more accurate for dating and should be used to determine the EDD.⁴ If the woman has been tracking her ovulation or knows her date of conception, these can be used to calculate her EDD as well. There are various methods used to track ovulation including over-the-counter ovulation kits, the use of basal body temperature chart with a coital record, as well as monitoring cervical mucus changes with coital record.

Often, the diagnosis of pregnancy begins when a woman presents with a positive home pregnancy test and cessation of menstrual periods. Only 4% of women give birth on the date predicted, which demonstrates that it is truly an estimate.⁵ Though there are several methods to calculate an EDD, the ones most commonly used are Naegele’s rule and ultrasound. The following questions help establish the EDD:

NOTE: If there is a leap year this may alter the EDD by one day less.

NOTE: Reassigning GA in the third trimester should be done with caution as there can be a 3 to 4 week range of accuracy. Using an accurate LMP for calculating the EDD is as reliable as using ultrasound in the second trimester. Ultrasound dating has a consistent margin of error of 8%.⁷

Many women cannot remember the first day of their LMP.² Many also mistake implantation bleeding for an unusually short “period.” Occasionally, a pregnancy is achieved during an amenorrheic period, when there is no menstruation. Amenorrhea, lack of menses, may occur in women experiencing certain conditions such as diabetes, thyroid problems, obesity, polycystic ovarian syndrome, or eating disorders. A woman who is exclusively breastfeeding will often have amenorrhea. Some women do not have regular 28-day cycles due to a longer follicular phase, thus affecting timing of ovulation earlier or later than day 14. Certain types of hormonal contraception may also lead to incorrect calculation of the date of ovulation.

Evaluation of fetal physical movements, FHR, and amniotic fluid production are currently used to predict fetal well-being at the time the testing is done. It is considered 99.8% predictive that fetal death is unlikely to occur within 1 week of a normal result.⁸ For additional information regarding electronic fetal monitoring, see Module 7.

Fetal activity requires oxygen consumption. When subjected to a hypoxic occurrence, one of the first fetal physiologic adjustments made is to economize movement. Compromise of fetal oxygenation elicits an adaptive response to decrease activity, thereby decreasing oxygen need.
This adaptive response can result from a physiologic or a pathophysiologic event. Fetal movements serve as an indirect measure of current central nervous system function. Maternal perception of fetal body movement has been used as a sign of fetal well-being. The goal of fetal movement counting is that when a woman identifies a decrease in her baby’s normal movement pattern she can report this to her provider, and additional antepartum testing can be initiated with the goal of preventing fetal death.⁹ Women who report decreased fetal movement have an incidence of stillbirth that is 60 times higher than women without this complaint. Various things can affect maternal perception of fetal movement such as fetal sleep cycles, maternal activity, and obesity.¹⁰ Though there is fetal movement during the first trimester, this is generally only noted through the use of ultrasound. The term “quickening” is used to describe the woman’s first fetal movement that is felt, usually like a small flutter.¹¹ Maternal perception of fetal movement generally starts in the second trimester. Primiparas typically begin to feel fetal movement between 18 and 22 weeks, while multiparous women often feel the fetus move earlier around 16 to 18 weeks.^11,12 Women who have an anterior placenta may begin to feel fetal movement later than those whose placenta has attached posteriorly. Fetal movement maximizes around 34 weeks GA, then decreases slightly due to the longer sleep cycles as the central nervous system matures.¹³

To date there is no specific level of fetal movement that can reliably identify a fetus at risk for fetal demise; there is generally a maternal awareness of what is normal movement for her own baby. There is no current evidence to support routine use of formal fetal kick count monitoring for women who are not at risk for chronic fetal hypoxia. Intrauterine fetal demise (IUFD), otherwise called stillbirth.¹¹ Formal fetal movement counting does not prevent all stillbirths, but there are those maternal or obstetric conditions that fall into a higher risk category, and these women may benefit by more formal fetal movement counts.⁶ Table 4.1 outlines recommended fetal surveillance testing for women and fetal high-risk conditions.

Adequate functioning of the uteroplacental unit is necessary for the fetus to accomplish and maintain patterns of healthy behavior. There are both maternal and fetal factors that can affect fetal breathing and limb movements (see Table 4.2).

NOTE: Women often report “less fetal movement” as term approaches. This change always requires careful evaluation, although what the mother perceives as “less movement” is often a result of less room in utero for the fetus to put “momentum” behind movements. The mother’s perception of a significant change always requires further exploration.

The normal fetus may move as many as 100 times per hour or as few as 4 times per hour. It is important to discuss with the woman the normal pattern of movement for her fetus. Attention should be given to any complaint of a decrease in the normal pattern of movement in the fetus. A period of decreased fetal movement commonly precedes fetal death, but the absence of perceived fetal movements does not necessarily indicate fetal death or compromise.

NOTE: Any time an expectant woman calls reporting decreased fetal activity, it requires follow-up.

Far too many expectant mothers avoid seeking care because they do not trust what they feel. Many have no prior frame of reference for what they are experiencing, but they also fear being seen as bothersome or a worrier. Anyone who might be a first-line contact for the expectant woman should demonstrate caring and concern.

If a mother calls reporting decreased fetal movement, explore her background for normalcy. Ask how today’s fetal movements compare with those of the previous day and the days preceding. When movement is present but perceived as lessening, you might instruct the mother to do one of the various methods for fetal kick counts. If after doing the fetal kick counts the mother has not had a minimum number of perceived fetal movements, then she should be instructed to come into the office or hospital for further evaluation.

Fetal movement counts have been utilized in the past as a simple, inexpensive, and noninvasive means of fetal surveillance for pregnant women. It can be done at home and has no contraindications. The rationale for fetal movement counting is the hope that fetal death can be prevented by acting immediately when there is a decrease in fetal movement. However, limitations of the test include the fact that the ideal number of movements or kicks has not been established, nor has the ideal duration for movement counting been clearly defined.¹⁶ Additionally, the period between decreased fetal movement and fetal death may be too short for timely intervention in some clinical situations such as placental abruption or cord accidents.

Despite the fact that there is not enough evidence to recommend formal fetal movement counts for all expectant women, they are widely prescribed in both low- and high-risk women.³ Fetal movement counts in high-risk women may begin as early as 28 weeks’ gestation and in low-risk women at 32 to 36 weeks’ gestation.

Many different methods have been devised to assess fetal movement. The intent of all methods is to have the expectant woman achieve a daily awareness of the patterns and level of activity exhibited by her baby in utero. One of the most popular is the “count to 10” method. This method requires that the mother dedicate 1 hour or less every day to tracking her baby’s movements.¹⁶