Does a discrepancy between gestational age determined by biparietal diameter and last menstrual period sometimes signify early intrauterine growth retardation?

First-trimester biomarkers and the risk of cerebral palsy

BACKGROUND

Cerebral palsy (CP) is the most common severe motor disability and a manifestation of early brain damage.

AIMS

To analyze if abnormal levels of first-trimester biomarkers were associated with CP. Furthermore, to investigate their clinical applicability in early predicting of CP.

STUDY DESIGN

Nationwide cohort study.

SUBJECTS

We included 258.057 singleton live births, born during 2008-2013 with completed first-trimester assessments.

OUTCOME MEASURES

Data on beta subunit of human chorionic gonadotropin (beta-hCG), pregnancy-associated plasma protein-A (PAPP-A), nuchal translucency thickness, and biparietal diameter (BPD) were converted to multiple of the medians (MoM). Associations were analyzed by comparing mean and extreme levels between pregnancies with and without CP. All CP diagnoses were validated by trained neuropediatricians. Logistic regression was used to create an early prediction model.

RESULTS

The mean beta-hCG value was significantly lower in pregnancies with CP (0.96MoM [95% CI 0.91-1.02] vs 1.04MoM [1.04-1.04], p = 0.01) and the mean PAPP-A value tended to be lower (0.96MoM [0.91-1.01] vs 1.01MoM [1.00-1.01], p = 0.07). Moreover, fetuses that developed CP more likely had a BPD measurement below the fifth percentile (7.5% vs 5%, p = 0.045). The final prediction model had poor discrimination.

CONCLUSIONS

Pregnancies with CP tend to have lower values of beta-hCG and PAPP-A in the first trimester, however, the associations are mediated differently. Nonetheless, abnormal levels of the most common first-trimester biomarkers only have weak associations with CP; resulting in inadequate predictive abilities when included in an early prediction model.

Second-trimester fetal head circumference in more than 350 000 pregnancies: Outcome and suggestion for sex-dependent cutoffs for small heads

OBJECTIVE

To explore the relationship between small fetal second-trimester head circumference (HC) and pregnancy outcome and identify a cutoff point for offering genetic testing.

METHOD

Data from second-trimester scans in Denmark were linked to national registers. Fetuses with anomalies diagnosed before this scan were excluded. Fetuses were grouped according to HC z-score.

RESULTS

We included 352 515 singleton fetuses. The mean HC was significantly larger among males than among females with z-scores averaging 0.52 more in males. Small HC was associated with chromosomal anomaly, malformations of the CNS and heart, miscarriage/perinatal death, termination, preterm delivery, and intrauterine growth restriction (test for trend: P < .001 for all outcomes). Fetuses in the group with z-score less than -3 had the highest incidence of adverse outcome, irrespective of fetal sex. In the groups with z-scores between -3 and -2.5, and between -2.5 and -2, risk of adverse outcome was lower for females than males for all outcome categories.

CONCLUSION

Small HC in second trimester is a prognostic marker for adverse outcome. The smaller the HC, the higher the risk of adverse outcome. We suggest an HC cutoff point of -2 SD for males and -2.5 SD for females for offering genetic testing.

Slow fetal growth between first and early second trimester ultrasound scans and risk of small for gestational age (SGA) birth

Objectives

To investigate the association between fetal growth between first and early second trimester ultrasound scan and the risk of severe small for gestational age (SGA) birth.

Methods

This cohort study included 69 550 singleton pregnancies with first trimester dating and an early second trimester growth scan in Stockholm and Gotland Counties, Sweden between 2008 and 2014. Exposure was difference in biparietal diameter growth between observed and expected at the second trimester scan, calculated by z-scores. Risk of birth of a severe SGA infant (birth weight for gestational age by fetal sex less than the 3^rd centile) was calculated using multivariable logistic regression analysis and presented as adjusted odds ratio (aOR).

Results

Parietal growth less than 2.5 percentile between first and second trimester ultrasound examination was associated with elevated risk of being born severe SGA. (aOR 1.67; 95% Confidence Interval 1.28–2.18). The risks of preterm severe SGA (birth before 37 weeks) and term severe SGA (birth 37 weeks or later) were at similar levels, and risk of severe SGA were also elevated in the absence of preeclampsia, hypertensive diseases or gestational diabetes.

Conclusions

Fetuses with slow growth of biparietal diameter at ultrasound examination in early second trimester exhibit increased risk of being born SGA independent of gestational age at birth and presence of maternal hypertensive diseases or diabetes mellitus.

Fetal growth and cardio-metabolic risk factors in the 20-year-old offspring

OBJECTIVE

To investigate the association between prenatal growth patterns as estimated by biparietal diameter and cardio-metabolic risk at 20 years.

DESIGN

Follow-up study.

SETTING

Denmark 1988-2009.

POPULATION

Two cohorts of children born between 1988 and 1990 (n=707) and followed up in 2008-2009 (n=333-509).

METHODS

We have access to biparietal diameter from early ultrasound scan and birthweight. For each gender, biparietal diameter and birthweight, gestational age-specific growth-z-scores were calculated. A change in growth trajectory was depicted as a shift in z-score for the two growth measures. Multiple linear regression modeling was used to estimate associations between biparietal diameter and birthweight z-scores and later cardio-metabolic risk factors as well as estimating whether changing growth trajectory was associated with later cardio-metabolic risk.

MAIN OUTCOME MEASURES

Self-reported anthropometrics and clinically measured blood pressure, heart rate and biochemical measures associated with cardio-metabolic health.

RESULTS

After adjustments, biparietal diameter was not associated with any of the outcomes. Birthweight was positively associated with both adult height and weight and inversely associated with insulin, triglyceride and insulin resistance. Also, the data indicated a U-shaped association between growth in the second half of pregnancy and adult body mass index among individuals with a low biparietal diameter in mid-pregnancy.

CONCLUSION

Different patterns of intrauterine growth may be associated with later risk of cardio-metabolic disease.

Validation of obstetric estimate using early ultrasound: 2007 California birth certificates

BACKGROUND

Obstetric estimate (OE) of gestational age, recently added to the standard US birth certificate, has not been validated. Using early ultrasound-based gestational age (prior to 20 weeks gestation) as the criterion standard, we estimated the prevalence of preterm delivery and the sensitivity and positive predictive value (PPV) of gestational age estimates based on OE.

METHODS

We analyzed 165 148 singleton livebirth records (38% of California livebirths during the study period) with linked early ultrasound information from a statewide California prenatal screening programme. OE of gestational age estimates was obtained from birth certificates.

RESULTS

Prevalence of preterm delivery (<37 weeks gestation) was higher based on early ultrasound (8.1%) compared with preterm delivery based on OE (7.1%). Sensitivity for preterm birth when using OE for gestational age was 74.9% (95% confidence interval [CI] [74.1, 75.6]), and PPV was 85.1% (95% CI [84.4, 85.7]). Incongruence, defined as a ≥ 14-day difference between early-ultrasound-derived gestational age and OE, was 3.4%.

CONCLUSIONS

OE reported on the birth certificate may underestimate the prevalence of preterm delivery, particularly among women of non-Hispanic non-white race and ethnicity and women with lower educational attainment, public insurance at time of delivery, and missing prepregnancy BMI. Additional validation studies in other samples of births are needed.

Correction of systematic bias in ultrasound dating in studies of small-for-gestational-age birth: an example from the Iowa Health in Pregnancy Study

The authors examined whether early ultrasound dating (≤20 weeks) of gestational age (GA) in small-for-gestational-age (SGA) fetuses may underestimate gestational duration and therefore the incidence of SGA birth. Within a population-based case-control study (May 2002-June 2005) of Iowa SGA births and preterm deliveries identified from birth records (n = 2,709), the authors illustrate a novel methodological approach with which to assess and correct for systematic underestimation of GA by early ultrasound in women with suspected SGA fetuses. After restricting the analysis to subjects with first-trimester prenatal care, a nonmissing date of the last menstrual period (LMP), and early ultrasound (n = 1,135), SGA subjects' ultrasound GA was 5.5 days less than their LMP GA, on average. Multivariable linear regression was conducted to determine the extent to which ultrasound GA predicted LMP dating and to correct for systematic misclassification that results after applying standard guidelines to adjudicate differences in these measures. In the unadjusted model, SGA subjects required a correction of +1.5 weeks to the ultrasound estimate. With adjustment for maternal age, smoking, and first-trimester vaginal bleeding, standard guidelines for adjudicating differences in ultrasound and LMP dating underestimated SGA birth by 12.9% and overestimated preterm delivery by 8.7%. This methodological approach can be applied by researchers using different study populations in similar research contexts.

Early childhood development when second-trimester ultrasound dating disagrees with last menstrual period: a prospective cohort study

BACKGROUND

When an ultrasound-based estimate of gestational age (GA) is less (greater) than an estimate based on a definite last menstrual period, the fetus may grow slower (faster) than average. While the association between these discrepancies in GA estimates and adverse perinatal outcomes has been examined extensively, there is scant evidence about long-term effects, such as child neurodevelopment.

METHODS

Using data from a prospective cohort study titled, NICHD Study of Successive Small-for-Gestational Age Births, we examined if GA discrepancies in early second trimester of pregnancy (17 weeks' gestation) are associated with: (1) impaired motor and mental function at 13 months (measured using Bayley Scales of Infant Development (Bayley)), and (2) impaired cognitive development at five years (assessed by Wechsler Preschool and Primary Scale of Intelligence - Revised Intelligence Quotient (WPPSI-R)) in the infant. The study population consisted of 572 (30% of the overall sample of 1,945) women who presented for prenatal care in Norway and Sweden between 1986 and 1988.

RESULTS

Our results showed that GA discrepancies in early second trimester are significantly associated with birthweight. We found no significant relationship, however, with the Bayley development scores at 13 months and with the WPPSI-R IQ measures at five years.

CONCLUSIONS

GA discrepancies at 17 weeks' gestation are not associated child neurodevelopment. These discrepancies do, however, relate to birthweights, providing a basis for detecting fetal growth patterns early in the second trimester of pregnancy. Our study, however, was unable to evaluate the impact of first-trimester discrepancies on impaired neurodevelopment in the infant.

Early fetal size and growth as predictors of adverse outcome

OBJECTIVE

To evaluate the association between fetal size and growth between the first and second trimesters and subsequent adverse pregnancy outcome.

METHODS

A cohort was created of 7,642 singleton pregnancies cared for in three obstetric units associated with Copenhagen University. Data were obtained from ultrasound measurements at 11-14 weeks (crown-rump length, biparietal diameter) and 17-21 weeks (biparietal diameter). Fetal size was assessed by gestation-specific z scores, and fetal growth between the first and second trimester was calculated individually using conditional centiles. The main outcome measures were preterm delivery, smallness for gestational age, and perinatal death.

RESULTS

Slow growth of the biparietal diameter less than the 10th and less than the 2.5th conditional centiles between first and second trimesters occurred in 10.4% and 3.6% of the population, respectively. Biparietal diameter growth less than the 10th centile was associated with perinatal death before 34 weeks (risk 0.5% compared with 0.04%, odds ratio [OR] 16.0, confidence interval [CI] 2.9-88.7). Biparietal diameter growth less than the 2.5th centile was the best predictor of perinatal death at any gestation, with a positive likelihood ratio of 4.7 and an OR of 7.3 (CI 2.4-22.2). In contrast, the biparietal diameter, dated by crown-rump length, did not have an increased risk of perinatal death; however, there was a mildly increased risk of small for gestational age birth weight (less than the 10th customized centile) if the biparietal diameter was below the 10th centile in the first trimester (risk 17% compared with 12%, OR 1.5, CI 1.2-1.8) or in the second trimester (risk 15.8% compared with 12.4%, OR 1.3, CI 1.1-1.5).

CONCLUSION

Slow growth of the fetal biparietal diameter between the first and second trimesters of pregnancy is a strong predictor of perinatal death before 34 weeks.

Fetal growth between the first and second trimesters and the risk of adverse pregnancy outcome

OBJECTIVES

To relate growth rate of the biparietal diameter (BPD) between the first and second trimesters to the risk of perinatal death, intrauterine growth restriction (IUGR), macrosomia, preterm/post-term delivery and pre-eclampsia.

METHODS

In this retrospective study, we analyzed sonographic BPD measurements at 11-14 and 17-21 weeks from 8215 singleton pregnancies in the Copenhagen First Trimester Study. Growth rate was defined as millimeters of growth per day between the two measurements and was dichotomized into growth rates < 2.5(th) vs. 2.5(th)-97.5(th) centiles, and > 97.5(th) vs. 2.5(th)-97.5(th) centiles. Odds ratios (OR) and 95% CIs for adverse outcome were calculated.

RESULTS

Fetuses with growth rates < 2.5(th) centile had an OR of 4.79 (95% CI, 1.43-15.99) for perinatal death and an OR of 2.64 (95% CI, 1.51-4.62) for birth weight < sonographically estimated mean fetal weight (adjusted for gestational age) - 2 SD. Fetuses with growth rates > 97.5(th) centile had an OR of 2.83 (95% CI, 1.58-5.06) for birth weight > mean + 2 SD and an OR of 2.30 (95% CI, 1.15-4.59) for delivery in weeks 34-36. Growth rate showed no association with pre-eclampsia.

CONCLUSIONS

There is a significant relationship between the growth rate of BPD from the first to the second trimester and adverse pregnancy outcome. Low growth rates are associated with an increased OR for perinatal death and IUGR, while high growth rates are associated with an increased OR for macrosomia and preterm delivery.

A comparison of LMP-based and ultrasound-based estimates of gestational age using linked California livebirth and prenatal screening records

Although early ultrasound (<20 weeks' gestation) systematically underestimates the gestational age of smaller fetuses by approximately 1-2 days, this bias is relatively small compared with the large error introduced by last menstrual period (LMP) estimates of gestation, as evidenced by the number of implausible birthweight-for-gestational age. To characterise this misclassification, we compared gestational age estimates based on LMP from California birth certificates with those based on early ultrasound from a California linked Statewide Expanded Alpha-fetoprotein Screening Program (XAFP). The final sample comprised 165 908 women. Birthweight distributions were plotted by gestational age; sensitivity and positive predictive value for preterm rates according to LMP were calculated using ultrasound as the 'gold standard'. For gestational ages 20-27 and 28-31 weeks, the LMP-based birthweight distributions were bimodal, whereas the ultrasound-based distributions were unimodal, but had long right tails. At 32-36 weeks, the LMP distribution was wider, flatter, and shifted to the right, compared with the ultrasound distribution. LMP vs. ultrasound estimates were, respectively, 8.7% vs. 7.9% preterm (<37 weeks), 81.2% vs. 91.0% term (37-41 weeks), and 10.1% vs. 1.1% post-term (>or=42 weeks). The sensitivity of the LMP-based preterm birth estimate was 64.3%, and the positive predictive value was 58.7%. Overall, 17.2% of the records had estimates with an absolute difference of >14 days. The groups most likely to have inconsistent gestational age estimates included African American and Hispanic women, younger and less-educated women, and those who entered prenatal care after the second month of pregnancy. In conclusion, we found substantial misclassification of LMP-based gestational age. The 2003 revised US Standard Certificate of Live Birth includes a new gestational age item, the obstetric estimate. It will be important to assess whether this estimate addresses the problems presented by LMP-based gestational age.

The impact of maternal smoking on fetal and infant growth

BACKGROUND

Low birth weight is associated with accelerated postnatal growth and adverse adult health outcomes. Maternal smoking is a major risk factor for low birth weight. This study aims to assess: Pre- and postnatal growth associated with maternal smoking compared to other risk factors for low birth weight. The effect of reduction of maternal smoking on growth.

SUBJECTS

A cohort (n=269) followed with ultrasound measurements in the third trimester and postnatal anthropometric measurements until 6 months of age. Mothers were interviewed about their smoking habits at 18 and 28 weeks of pregnancy.

RESULTS

Maternal smoking was associated with a greater reduction in birth length SDS than other causes of equally reduced birth weight (mean difference: -0.25 SDS, P=0.013). The adjustment of gestational age, based on bi-parietal diameter at an early dating scan, indicated that mothers who reduced smoking carried smaller fetuses than mothers who continued to smoke heavily (mean difference=2.6 days, P=0.012). Birth weights in these two groups were similar (P=0.87). However at 3 months of age, reduced smoking was associated with lower weight (mean difference=-0.38 SDS, P=0.045).

CONCLUSIONS

Maternal smoking was associated with a reduction of linear growth, which was more marked than that of other risk factors, and which seemed to occur before the 3rd trimester. The results indicated a beneficial effect of reduction of smoking upon third trimester growth, and that the decision to reduce smoking in mid-pregnancy may be influenced by early fetal size.

Predicting antepartum stillbirth

PURPOSE OF REVIEW

Rates of stillbirth in the developed world have been static or rising in recent years. Clinical prediction of stillbirth risk may allow interventional studies.

RECENT FINDINGS

The most prevalent independent risk factors are nulliparity, advanced age and obesity. These are increasingly prevalent in the developed world. Obesity is particularly associated with stillbirth at term and after term. Pregestational diabetes is a major risk factor for stillbirth and these women are usually offered intensive surveillance during pregnancy. Despite this, a recent national study in the UK demonstrated a fourfold excess of stillbirth, with 80% unrelated to congenital abnormality. Studies of association between previous caesarean section and subsequent stillbirth risk are inconsistent, although in data sources with detailed information, the association has been confirmed. Global analyses of stillbirth risk demonstrate that 98% occur in the developing world and that many are due to potentially preventable causes. A randomized controlled trial of very simple educational interventions was associated with a 30% lower risk of stillbirth.

SUMMARY

Relatively simple interventions may be successful in reducing the global burden of stillbirth. Further biological understanding of the causes of stillbirth is required to reduce the burden of the disease in the developed world.

Determinants and consequences of discrepancies in menstrual and ultrasonographic gestational age estimates

OBJECTIVES

To assess the association between maternal and fetal characteristics and discrepancy between last normal menstrual period and early (<20 weeks) ultrasound-based gestational age and the association between discrepancies and pregnancy outcomes.

DESIGN

Hospital-based cohort study.

SETTING

Montreal, Canada.

SAMPLE

A total of 46,514 women with both menstrual- and early ultrasound-based gestational age estimates.

MAIN OUTCOME MEASURES

Positive (last normal menstrual period > early ultrasound, i.e. menstrual-based gestational age is higher than early ultrasound-based gestational age, so that the expected date of delivery is earlier with the menstrual-based gestational age) discrepancies > or =+7 days, mean birthweight, low birthweight, stillbirth and in-hospital neonatal death.

RESULTS

Multiparous mothers and those with diabetes, small stature or high pre-pregnancy body mass index were more likely to have positive discrepancies. The proportion of women with discrepancies > or =+7 days was significantly higher among chromosomally malformed and female fetuses. The mean birthweight declined with increasingly positive differences. The risk of low birthweight was significantly higher for positive differences. Associations with fetal growth measures were more plausible with early ultrasound estimates.

CONCLUSIONS

Although most discrepancies between last normal menstrual period- and early ultrasound-based gestational age are attributable to errors in menstrual dating, our results suggest that some positive differences reflect early growth restriction.

Prematurity and fetal growth restriction

Assessment of the growth status of the fetus and neonate is an essential component of perinatal care. It requires a distinction to be made between physiological and pathological factors, and the prediction of the optimal growth that a baby can achieve in a normal, uncomplicated pregnancy. Such an individually customised standard can now be easily calculated by computer: it needs to be accurately dated, individually adjusted for physiological characteristics, exclude pathological factors such as smoking, and be based on a fetal weight trajectory derived from normal term pregnancies. Application of a customised standard to calculate the growth status of preterm babies gives us freshly insights into the causes of prematurity. Fetal growth restriction is seen as a strongly associated factor, which is often present before the onset of spontaneous preterm labour. This raises the question whether, in many instances, the initiation of parturition should be seen as a fetal adaptive response aimed at escaping an unfavourable intrauterine environment. These concepts have implications for the understanding of the pathophysiology of preterm labour, as well as its clinical management.

Fetal age assessment based on ultrasound head biometry and the effect of maternal and fetal factors

BACKGROUND

Maternal height and weight have increased during the past 20 years, as has birthweight. The aim of the present study was to establish new reference charts for gestational age (GA) assessment using fetal biparietal diameter (BPD) and head circumference (HC), and to determine the effect of maternal and fetal factors on age assessment.

METHODS

This was a prospective, cross-sectional study of 650 healthy women with regular menstrual periods and singleton uncomplicated pregnancies, recruited after written consent. BPD (outer-outer) and HC were measured at 10-24 weeks of gestation. We used regression analysis to construct mean curves and assess the effect of maternal and fetal factors on age assessment.

RESULTS

BPD and HC were successfully measured in 642 participants. Using BPD and HC before 20 weeks, the new charts gave 3-8 days higher GA assessment than the charts presently in use, and <1 day difference compared to other recently established charts. Maternal age, multiparity, fetal gender, breech position and shape of fetal head affect GA estimation by 1-2 days when using BPD (p = 0.0001-0.02). Only maternal age and fetal gender affected GA estimation when using HC (</= 1 day, p = 0.001).

CONCLUSIONS

Our new charts for assessing gestational age based on fetal head biometry are notably different from charts presently in use. Maternal and especially fetal factors affect gestational age assessment when using BPD, but less so for the HC method, which is suggested as the more robust method.

First trimester origins of fetal growth impairment

The timing of factors that lead to disorders of fetal growth have been studied for many years. Previous studies have focused on disorders of the "second wave" of trophoblast invasion of myometrial arterioles and on fetal weight gain in the third trimester. Over the last 5 years, clinical studies have shown associations between first trimester ultrasound and biochemical parameters and the risk of later adverse perinatal outcome. First trimester growth restriction is associated with an increased risk of low birth weight, low birth weight percentile for gestational age and extremely preterm birth. This may reflect a defect in early pregnancy placentation and later adverse outcome. Consistent with this hypothesis, low first trimester circulating maternal concentrations of pregnancy-associated plasma protein A, a trophoblast-derived regulator of the insulin-like growth factor system, are associated with an increased risk of later stillbirth, growth restriction, pre-term birth and pre-eclampsia. Even among healthy women having normal pregnancies, first trimester circulating concentrations of pregnancy-associated plasma protein A correlate with the timing of spontaneous labor and the eventual birth weight. These analyses suggest that in some women complications of late pregnancy have their origins in the very earliest weeks of gestation and precede first attendance for prenatal care.

Adverse obstetric outcome in fetuses that are smaller than expected at second trimester routine ultrasound examination

BACKGROUND

Adverse obstetric outcome in fetuses that are smaller than expected at second trimester routine ultrasound examination.

AIM

To assess the obstetric outcome when the interval between the estimated date of delivery by last menstrual period and the estimated date of delivery by second trimester ultrasound exceeds 14 days.

MATERIALS AND METHODS

Population-based prospective cohort study. Included were all women (n = 16 302) with a singleton pregnancy, in one Norwegian county from 1989 to 1999, with a reliable menstrual history and whose second trimester ultrasound examination was conclusive with a 35-60-mm biparietal diameter.

RESULTS

Adverse outcome was defined as preterm birth (< 37 weeks), perinatal death, low birthweight (< 2500 g) and small-for-gestational age (< 2 standard deviation). The risk for perinatal death (odds ratio = 2.3), preterm birth (odds ratio = 1.7), low birth weight (odds ratio = 1.5), and small-for-gestational age (odds ratio = 1.5) was highly significantly increased in deliveries where the discrepancy between the two terms was more than 14 days. The increased risk is not explained by differences in parity, maternal age, smoking, fetal malformations, or use of oral contraceptives before pregnancy.

CONCLUSION

Fetuses that are smaller than expected at the mid-second trimester ultrasound corresponding to a discrepancy of more than 14 days have an increased risk for adverse obstetric outcome.

Intrauterine growth restriction

Pathophysiological processes underlying intrauterine growth restriction are very complex and poorly understood. Growth restricted fetuses are at risk of hypoxia and, therefore, an early diagnosis of intrauterine growth restriction is important for initiation of fetal surveillance. Application of a three-dimensional ultrasound method for estimation of fetal weight promises better precision. Use of conditional standard deviation scores of fetal biometric variables has been suggested for improved individualized evaluation of intrauterine growth. Application of umbilical artery Doppler velocimetry in the clinical management of growth-restricted fetuses after 32 weeks of gestation leads to decreased perinatal mortality and lower rates of obstetric interventions. Evaluation of fetal state before 32 weeks is difficult and should include Doppler examination of placental circulation and several fetal arterial and venous vessel beds. In addition, recordings of short-term variability of fetal heart rate and biophysical profile have been suggested for fetal surveillance. Important new data on the time sequence of Doppler changes in various vessels of compromised very preterm growth restricted fetuses have been presented, which will enable the establishment of clinical management protocols for evaluation in prospective randomized studies.

A discrepancy between gestational age estimated by last menstrual period and biparietal diameter may indicate an increased risk of fetal death and adverse pregnancy outcome

OBJECTIVE

To determine if the discrepancy between gestational age estimated by last menstrual period and by biparietal diameter (GALMP - GABPD) is associated with adverse pregnancy outcome.

DESIGN

Population-based follow up study.

POPULATION

Singleton pregnancies were studied when a reliable date of last menstrual period and biparietal diameter measured between 12 and 22 weeks of gestation was available (n = 16,469).

METHODS

Logistic regression analysis and Kaplan-Meier survival analysis were used to analyse the association between GALMP - GABPD and adverse pregnancy outcome.

MAIN OUTCOME MEASURES

Adverse outcome was defined as abortion after 12 weeks of gestation, still-birth or postnatal death within one year of birth, delivery < 37 weeks of gestation, a birthweight < 2,500 g or a sex-specific birthweight lower than 22% below the expected.

RESULTS

The risk of death was more than doubled if GALMP - GABPD of > or = 8 days was compared with GALMP - GABPD of < 8 days (OR 2.2; 95% CI 1.6-3.1). The risk of death was a factor of 6.1 higher if GALMP - GABPD of > or = 8 days was combined with increased (> 2 x multiple of median) maternal alpha-fetoprotein measured in the 2nd trimester.

CONCLUSIONS

A discrepancy between GALMP and GABPD generally reflects the precision of the two methods used to predict term pregnancy. However, a positive discrepancy of more than seven days, particularly with high maternal alpha-fetoprotein, might indicate intrauterine growth retardation and an increased risk of adverse perinatal outcome.