Methods for Estimating the Due Date - ACOG
Your due date may not be your baby's birthday. Many health-care providers use a sonogram to pinpoint your due date, but don't be swayed by technology: A . first child LMP date was 26/12, ultrasound date was 19/12, he was born 20/12, so ultrasound was more accurate. Second child LMP date was. The estimated due date (EDD or EDC) is the date that spontaneous onset of labor is expected to occur. The due date may be estimated by adding days (9 months and 7 days) to the first day of the last menstrual period (LMP). Ultrasound uses the size of the fetus to determine the.
Guessing game, waiting game Though most women are given an official due date, it is often just a rough estimate. Only 5 percent of women deliver on their due date, according to American Academy of Pediatrics.
A healthy pregnancy is, on average, 40 weeks from the last menstrual period, but in reality, most babies come sometime between 37 and 42 weeks gestation. For many women, that five-week window creates a waiting game that can feel unbearable.
Women with little paid maternity leave may want to work until the last possible moment they can. Those whose due date has come and gone may wonder whether they should have labor induced with drugs. And pregnant women who already have other children often scramble to find child care during labor. But there haven't been reliable methods to tell a woman exactly when her baby is coming.
Cervical checks, in which a doctor manually feels the length and softness of the cervix with his or her fingers, are typically not very reliable, Berghella said.
Sonogram dating and birthdate - Servirege
However, studies have shown that women who have a short cervix, less than 1 inch 2. That made researchers wonder whether similar scans could be predictive during the homestretch of pregnancy. Measurable changes To answer that question, Berghella looked at five studies in which researchers used ultrasounds to measure cervical length of a total of pregnant women.
He found that among the women whose cervix was more than 1. By contrast, among the women whose cervixes were less than 0. When determined from the methods outlined in this document for estimating the due date, gestational age at delivery represents the best obstetric estimate for the purpose of clinical care and should be recorded on the birth certificate.
Sonogram dating and birthdate
For the purposes of research and surveillance, the best obstetric estimate, rather than estimates based on the last menstrual period alone, should be used as the measure for gestational age. Recommendations The American College of Obstetricians and Gynecologists, the American Institute of Ultrasound in Medicine, and the Society for Maternal—Fetal Medicine make the following recommendations regarding the method for estimating gestational age and due date: 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.
As soon as data from the last menstrual period LMPthe 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. Introduction An accurately assigned EDD early in prenatal care is among the most important results of evaluation and history taking.
This information is vital for timing of appropriate obstetric care; scheduling and interpretation of certain antepartum tests; determining the appropriateness of fetal growth; and designing interventions to prevent preterm births, postterm births, and related morbidities. Appropriately performed obstetric ultrasonography has been shown to accurately determine fetal gestational age 1.
Ultrasound Scans Can Tell When Baby Is Due
A consistent and exacting approach to accurate dating is also a research and public health imperative because of the influence of dating on investigational protocols and vital statistics. 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 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. Clinical Considerations in the Second Trimester Using a single ultrasound examination in the second trimester to assist in determining the gestational age enables simultaneous fetal anatomic evaluation.
Ultrasound dates or LMP dates- which are more accurate?? in Your Pregnancy | Forum | Huggies
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. Ultrasonography dating in the second trimester typically is based on regression formulas that incorporate variables such as the biparietal diameter and head circumference measured in transverse section of the head at the level of the thalami and cavum septi pellucidi; the cerebellar hemispheres should not be visible in this scanning plane the femur length measured with full length of the bone perpendicular to the ultrasound beam, excluding the distal femoral epiphysis the abdominal circumference measured in symmetrical, transverse round section at the skin line, with visualization of the vertebrae and in a plane with visualization of the stomach, umbilical vein, and portal sinus 8 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.
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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.
Conclusion Accurate dating of pregnancy is important to improve outcomes and is a research and public health imperative. 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. 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. Fetal Imaging Workshop Invited Participants.