Further details of the sociodemographic characteristics of the respondents are shown in Table 1. The mean gestational age at recruitment and antenatal booking for respondents was One hundred and sixty-seven One hundred and ninety-one The remaining eight women 1. On the other hand, All the women who responded positively Likewise, all the women who responded negatively Characteristics of respondents versus acceptance of labor induction for postdatism using menstrual dating. OR, odds ratio; CI, confidence interval. This study demonstrates that pregnant women in Enugu, Nigeria, have poor knowledge of the limits of accuracy of late pregnancy ultrasound scan in estimating the delivery date.

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• How is an ultrasound performed??
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• Methods for Estimating the Due Date?

This poor knowledge invariably translated into the observed perception of respondents toward induction of labor for postdatism, as more than half of the women This attitude poses a great challenge to perinatal care in our environment because an ultrasound scan is usually carried out in the third trimester when the margin of error is up to 3 weeks.

Late booking for antenatal care might have strongly contributed to the poor uptake 7. The recent proliferation of ultrasound scan services in our environment came with a wave of optimism that ultrasound scanning could accurately determine all aspects of fetal well-being, hence only the well-educated or informed could question or resist its results. This misconception is further worsened by uncontrolled purchasing and use of ultrasound scanning machines by poorly trained personnel who advertise themselves as sonologists or sonographers. What is even more worrisome is the increasing number of self-referrals for ultrasound by our pregnant women merely to know the EDD which they usually hold on to.

Legislation to regulate the acquisition and use of ultrasound by health professionals in the country may help to keep this problem in check.

Methods for Estimating the Due Date - ACOG

Such legislation should also discourage self-referral by pregnant women for ultrasound. This will further help to prevent our women from visiting poorly trained sonologists and guard against the possible effects of unreliable ultrasound scan results on maternal and neonatal health. Tertiary education was identified in this report as a strong determinant of acceptance of induction of labor for postdatism using the last menstrual date.

This may be explained by the expected impact of education on uptake of maternal and neonatal health services, as observed by previous authors. Also, the lesser educated are more likely to rely more on the impression created outside about a procedure like ultrasound, whether right or wrong. As pointed out by Olusanya et al, 12 the higher the educational status of the woman, the higher the social class, and this no doubt may explain the higher acceptance rate among women of higher social class than among women of lower social class.

This will help to reduce the incidence of prolonged pregnancy and its complications in our environment. The limitation of this study is that the willingness to accept labor induction was assumed to mean acceptance of induction of labor. It is likely that some of the respondents might have responded differently if their pregnancies were actually prolonged. However, the effect of this limitation on the study estimates is likely to be minimal.

Selection of respondents for this study was consecutive considering the short study period, and selection bias cannot be ruled out; a longer study period and use of probability sampling would have been more appropriate. The strength of the study is that it is a novel effort toward stimulating the interest of physicians involved in maternal care regarding the increasing wave of self-referral for ultrasound scan in pregnancy in our environment, and the strong value mothers attach to ultrasound scan dating.

In conclusion, this study shows that in cases where late pregnancy ultrasound scan-derived EDD is further on than the menstrual dating, most women seen in the antenatal clinics at the teaching hospitals in Enugu would not be willing to accept labor induction for postdatism based on their menstrual dating. This worrisome attachment to ultrasound scan dating is a challenge to the prevention of prolonged pregnancy and its complications in our environment.

Predictors of this attitude in our study were low educational status, low social class, and poor knowledge of the limitations of late pregnancy ultrasound scan dating. Antenatal health education should discourage self-referral for ultrasound scanning and emphasize the limitations of late ultrasound scan dating as well as the perinatal effects of prolonged pregnancy.

Educational campaigns are also encouraged regarding the need for early antenatal booking and accurate determination of EDD and gestational age during pregnancy.

What types of ultrasound are there?

National Center for Biotechnology Information , U. Int J Womens Health. Published online Feb This Committee Opinion outlines a standardized approach to estimate gestational age and the anticipated due date. However, there is great usefulness in having a single, uniform standard within and between institutions that have access to high-quality ultrasonography as most, if not all, U. Accordingly, in creating recommendations and the associated summary table, single-point cutoffs were chosen based on expert review.

Because this practice assumes a regular menstrual cycle of 28 days, with ovulation occurring on the 14th day after the beginning of the menstrual cycle, this practice does not account for inaccurate recall of the LMP, irregularities in cycle length, or variability in the timing of ovulation. It has been reported that approximately one half of women accurately recall their LMP 2—4. Accurate determination of gestational age can positively affect pregnancy outcomes.

For instance, one study found a reduction in the need for postterm inductions in a group of women randomized to receive routine first-trimester ultrasonography compared with women who received only second-trimester ultrasonography 5. A Cochrane review concluded that ultrasonography can reduce the need for postterm induction and lead to earlier detection of multiple gestations 6. Because decisions to change the EDD significantly affect pregnancy management, their implications should be discussed with patients and recorded in the medical record.

Measurements of the CRL are more accurate the earlier in the first trimester that ultrasonography is performed 11, 15— The measurement used for dating should be the mean of three discrete CRL measurements when possible and should be obtained in a true midsagittal plane, with the genital tubercle and fetal spine longitudinally in view and the maximum length from cranium to caudal rump measured as a straight line 8, Mean sac diameter measurements are not recommended for estimating the due date. Dating changes for smaller discrepancies are appropriate based on how early in the first trimester the ultrasound examination was performed and clinical assessment of the reliability of the LMP date Table 1.

For instance, the EDD for a pregnancy that resulted from in vitro fertilization should be assigned using the age of the embryo and the date of transfer. For example, for a day-5 embryo, the EDD would be days from the embryo replacement date. Likewise, the EDD for a day-3 embryo would be days from the embryo replacement date.

Using a single ultrasound examination in the second trimester to assist in determining the gestational age enables simultaneous fetal anatomic evaluation. With rare exception, if a first-trimester ultrasound examination was performed, especially one consistent with LMP dating, gestational age should not be adjusted based on a second-trimester ultrasound examination.

How well does fetal ultrasound predict the date of birth in Antigua and Barbuda?

Ultrasonography dating in the second trimester typically is based on regression formulas that incorporate variables such as. Other biometric variables, such as additional long bones and the transverse cerebellar diameter, also can play a role. Date changes for smaller discrepancies 10—14 days are appropriate based on how early in this second-trimester range the ultrasound examination was performed and on clinician assessment of LMP reliability. Because of the risk of redating a small fetus that may be growth restricted, management decisions based on third-trimester ultrasonography alone are especially problematic; therefore, decisions need to be guided by careful consideration of the entire clinical picture and may require close surveillance, including repeat ultrasonography, to ensure appropriate interval growth.

The best available data support adjusting the EDD of a pregnancy if the first ultrasonography in the pregnancy is performed in the third trimester and suggests a discrepancy in gestational dating of more than 21 days. As soon as data from the LMP, the first accurate ultrasound examination, or both are obtained, the gestational age and the EDD should be determined, discussed with the patient, and documented clearly in the medical record.

For the purposes of research and surveillance, the best obstetric estimate, rather than estimates based on the LMP alone, should be used as the measure for gestational age.

Assessment of Gestational Age by Ultrasound

The American College of Obstetricians and Gynecologists, the American Institute of Ultrasound in Medicine, and the Society for Maternal—Fetal Medicine recognize the advantages of a single dating paradigm being used within and between institutions that provide obstetric care. Table 1 provides guidelines for estimating the due date based on ultrasonography and the LMP in pregnancy, and provides single-point cutoffs and ranges based on available evidence and expert opinion. Goldenberg RL, Nelson K: Iatrogenic respiratory distress syndrome. Neonatal respiratory distress following elective delivery: Routine ultrasound screening for the prediction of gestational age.

Assessment of fetal maturity and dysmaturity. Ultrasound in managing the high-risk pregnancy. In Spellacy WD ed: Management of the High-Risk Pregnancy, pp — Baltimore, University Park Press, Clinical estimation of gestational age: Rules for avoiding preterm delivery. Ultrasound scanning of ovaries to detect ovulation in women. Variability of ovarian follicular growth in natural menstrual cycles. Growth and development of the human fetus prior to the twentieth week of gestation. Length and depth of the uterus and the diameter of the gestation sac in normal gravidas during early pregnancy.

Acta Obstet Gynecol Scand 50 suppl: Br J Obstet Gynaecol The ultrasonic measurement of fetal crown-rump length as a method of assessing gestational age. Underestimation of gestational age by conventional crown-rump length growth curves. The prediction of fetal maturity by ultrasonic measurement of the biparietal diameter. J Obstet Gynaecol Br Commonw Sonar BPD and fetal age: Definition of the relationship.

Campbell S, Newman GB: Growth of the fetal biparietal diameter during normal pregnancy. Sabbagha RE, Hughey M: Standardization of sonar cephalometry and gestational age. Analysis of percentile growth differences in two normal populations using same methodology. Hughey M, Sabbagha RE: Cephalometry by real time imaging: Am J Obstct Gynecol Analysis of biparietal diameter as an accurate indicator of gestational age. J Clin Ultrasound 8: A critical reevaluation of the relation to menstrual age by means of realtime ultrasound.

J Ultrasound Med 1: Improved prediction of gestational age from fetal head measurement. Relation to menstrual age. Campbell S, Wilken D: Ultrasonic measurement of fetal abdomen circumference in the estimation of fetal weight. Percentile ranks of sonar fetal abdominal circumference measurements. Fetal abdominal circumference as a predictor of menstrual age. A date-independent predictor of intrauterine growth retardation: Normal growth of the fetal biparietal diameter and the abdominal diameter in a longitudinal study.

Acta Obstet Gynecol Scand Ultrasound measurement of fetal limb bones. Assessment of gestational age in the second trimester by real-time ultrasound measurement of the femur length. Fetal femur length as a predictor of menstrual age. Estimation of gestational age from measurement of fetal long bones.

J Ultrasound Med 3: Ultrasonic evaluation of fetal ventricular growth. A new parameter for prenatal diagnosis and dating. A new way to estimate fetal age. Cerebellar measurements with ultrasonography in the evaluation of fetal growth and development. Prenatal sonographic assessment of the fetal thorax: A new biometric parameter for estimation of gestational age.

Sonographic appearance of the fetal heel ossification centers and foot length measurements provide independent markers for gestational age estimation. Sonar measurement of fetal crown-rump length as means of assessing maturity of first trimester of pregnancy.