Fetal Low Birth Weight Research Articles

Intracytoplasmic sperm injection and low body mass index independently associate with low fetal birth weight in singleton art cycles

Intracytoplasmic sperm injection and low body mass index independently associate with low fetal birth weight in singleton art cycles

Medium chain fatty acids in intrauterine growth restricted and small for gestational age pregnancies

Low birth weight is associated with an increased risk of heart disease, high blood pressure and diabetes in adult life. Fetal growth is determined by nutrient availability, which is related to placenta nutrient transport. Medium chain fatty acids (MCFAs) are a particular class of nutrients, known to be a readily available energy source. Until now no data are reported on these MCFAs in low birth weight fetus. This is a prospective study conducted in a tertiary center of prenatal diagnosis to investigate the maternal and fetal MCFAs levels in appropriate for gestational age (AGA), intrauterine growth restricted (IUGR), and small for gestational age (SGA) pregnancies. The plasmatic levels of MCFAs in AGA, IUGR and SGA mother–infant pairs were quantified by gas chromatography–mass spectrometry. The analytical method had a linearity range of 0.1–50 mg/L and a limit of quantification of 0.03 mg/L. Reduced fetal growth was defined as an estimated fetal weight below the 3rd–10th percentile for gestational age, with (IUGR) or without (SGA) fetal Doppler abnormalities. Maternal and fetal MCFAs plasma levels were significantly different among SGA, IUGR and AGA groups. Additionally, the observed MCFAs fetal to maternal ratio is >1 for IUGR group, whilst for SGA and AGA the fetal to maternal ratio is less than one. Changes in MCFAs levels in fetal and maternal plasma are not related to placental functionality or nutrients availability, suggesting the presence of a de novo biosynthesis.

Preeclampsia and the brain: neural control of cardiovascular changes during pregnancy and neurological outcomes of preeclampsia.

Preeclampsia (PE) is a form of gestational hypertension that complicates ∼5% of pregnancies worldwide. Over 70% of the fatal cases of PE are attributed to cerebral oedema, intracranial haemorrhage and eclampsia. The aetiology of PE originates from abnormal remodelling of the maternal spiral arteries, creating an ischaemic placenta that releases factors that drive the pathophysiology. An initial neurological outcome of PE is the absence of the autonomically regulated cardiovascular adaptations to pregnancy. PE patients exhibit sympathetic overactivation, in comparison with both normotensive pregnant and hypertensive non-pregnant females. Moreover, PE diminishes baroreceptor reflex sensitivity (BRS) beyond that observed in healthy pregnancy. The absence of the cardiovascular adaptations to pregnancy, combined with sympathovagal imbalance and a blunted BRS leads to life-threatening neurological outcomes. Behaviourally, the increased incidences of maternal depression, anxiety and post-traumatic stress disorder (PTSD) in PE are correlated to low fetal birth weight, intrauterine growth restriction (IUGR) and premature birth. This review addresses these neurological consequences of PE that present in the gravid female both during and after the index pregnancy.

Maternal and fetal outcomes in oocyte donation pregnancies.

Since the first successful use of donated oocytes in 1984, the number of oocyte donationcycles in Europe and the USA has dramatically increased. Consequently, there has been increasing interest in the impact of oocyte donation on maternal and fetal outcomes. The aim of this review was to summarize the literature regarding maternal and fetal outcomes from pregnancies conceived through oocyte donation. Identification of relevant publications was through research within the Embase Medline and PubMed databases, the Google-indexed scientific literature and periodic specialized magazines from the on-line Library Service of the University of Milan. Oocyte donation seems to be independently associated with a higher rate of pregnancy-induced hypertension and pre-eclampsia. An explanatory hypothesis is that an immunological maladaptation causes placenta-mediated disorders in oocyte donation pregnancies. The risks are even higher in twin pregnancies. Oocyte donation also seems to be associated with lower fetal birthweight. However, after adjusting for obstetric complications, most studies report less pronounced differences in birthweight or no dissimilarities. The incidence of cesarean section is increased without clear clinical indications. Oocyte donation pregnancies are associated with a higher rate of placental disorders of pregnancy, such as gestational hypertension and pre-eclampsia. The risk of poorer neonatal outcomes is increased in oocyte donation pregnancies compared to otherin-vitro fertilization pregnancies. Poorer outcomes have been demonstrated especially for twin pregnancies and in association with previous chronic pathologies or the development of obstetrics complications.

CLINICAL AND MORPHOLOGICAL CHARACTERIZATION OF FETOPLACENTAL COMPLEX IN PREGNANT PATIENTS WITH DIFFUSE TOXIC GOITER

Актуальность. Течение беременности и родов у пациенток с диффузным токсическим зобом (ДТЗ) часто осложняется преэклампсией, фетоплацентарной недостаточностью, преждевременной отслойкой плаценты, сопряжено с повышенной материнской и перинатальной смертностью.

Pemphigoid Gestationis: A Rare Dermatosis of Pregnancy

Pemphigoid gestationis is a rare dermatosis of pregnancy that often goes unrecognized or misdiagnosed. It can lead to adverse fetal outcomes including preterm delivery, low fetal birth weight, and even neonatal pemphigoid gestationis1. As such, proper diagnosis and management is critical in reducing fetal risk.

Correlation of CRP levels in third trimester with fetal birth weight in preeclamptic and normotensive pregnant women.

To evaluate the levels of C-reactive protein, an inflammatory marker in preeclamptic and normotensive pregnant women and to determine its correlation with fetal birth weight. Cross-sectional analytical study. Unit of Obstetrics and Gynaecology, Shaikh Zayed Hospital and Gynaecological Unit II of Jinnah Hospital, Lahore, from December 2011 to May 2012. The participants included 60 cases with preeclampsia and 60 normotensive pregnant women, all in their third trimester. All the participants were in the age group of 20 - 40 years and had a BMI range of 18 - 25. High sensitive C-reactive protein (hsCRP) levels were measured by Enzyme Link Immunosorbent Assay. Statistical analysis was done using SPSS (version 15). The values were considered significant at 0.05 level of significance. C-reactive protein levels were significantly high (p < 0.001) in the preeclamptic group with a median value of 8.8 (0.3 - 25.5) as compared to 5.4 (0.24 - 9.8) mg/l in the normotensive women. The birth weight of babies was also significantly low in the preeclamptic group. The high CRP levels were negatively correlated with fetal birth weight in preeclamptic group. Elevated C-reactive protein levels in the preeclamptic pregnant women is a part of an exaggerated maternal systemic inflammatory response, and correlates with low fetal birth weight.

The recommendations of the American Institute of Medicine (IOM) for normal and underweight women to reduce the risk of low birth weight

ObjectiveThe recommendations of the American Institute of Medicine (IOM) were revised recently in order to enhance maternal and neonatal health. The aim of our study was to investigate the risk of low birth weight (LBW) among women who follow the IOM recommendations. Materials and methodsGestational weight gain (GWG) and rate of weight gain (RWG) across the different periods of pregnancy among women who delivered LBW fetuses were analyzed retrospectively. The logistic regression was used to analyze the risk of LBW and to identify recommendations. ResultsFrom January 2008 to December 2009, 117 out of 4924 (2.4%) women delivered term LBW fetuses. After exclusions, 88 LBW and 91 control subjects were enrolled into the study. There was increased risk of cesarean delivery [odds ratio (OR) with 95% confidence interval (CI): 2.53 (1.33–4.83)] and neonatal asphyxia within 7 days of birth [OR 95% CI: 5.71 (1.21–26.83)] for the LBW group compared with the control group. Normal weight women [body mass index (BMI): 18.5–24.9 kg/m2] who followed the GWG and RWG recommendations of the IOM had no increased risk of LBW. However, there was a two-to three-fold increased LBW risk among normal weight women who followed the IOM guidelines when, during the 2nd trimester, their GWG was ≤7 kg [OR 95% CI: 2.21 (1.28–6.49)] or their RWG was ≤0.45 kg/week [OR 95% CI: 3.14 (1.32–7.47)]. Among underweight women (BMI < 18.5 kg/m2), if, during the 2nd and 3rd trimesters, they followed the lower range of the GWG and RWG recommendations of the IOM there was a five-fold increased risk of LBW if the GWG was ≤13 kg [OR 95% CI: 5.29 (1.61–25.51)]; or the RWG was ≤0.45 kg/week [OR 95% CI: 5.35 (1.61–24.66)]. ConclusionFor underweight women, it is suggested that they follow the upper range of the IOM recommendation in order to avoid LBW. For normal weight women, although the IOM guidelines provide a good basis, it is suggested that they carefully follow the recommended GWG and the RWG values during the 2nd trimester, which is a very important period for fetal growth.

Rheologic results and their correlation to hemostatic changes in patients with moderate and severe preeclampsia: An observational cross-sectional study

Previous study have shown an association between failure of physiological hemodilution during 2nd trimester and an increased risk for the development of subsequent pregnancy complications such as early birth, birth of a growth retarded newborn (IUGR), low fetal birth weight and preeclampsia. The latter complication in particular goes along with dramatic changes in the placental perfusion as well as systemic maternal blood flow. Severity of preeclampsia may be preceded by distinct impaired hemodilution and reflected by the results of rheological parameters. A subgroup analysis was performed in a community based retrospective study of 4,985 consecutively recorded singleton pregnant women of whom 423 had preeclampsia. Mean 2nd trimester hemoglobin levels and blood rheological results at the time of delivery were assessed and compared in women with moderate and severe preeclampsia. Mean 2nd trimester hemoglobin levels were calculated from the maternal records. Rheological variables included plasma viscosity (KSPV 1 Fresenius) and Red blood cell aggregation in stasis and under low shear conditions (MA1-Aggregometer; Myrenne). According to the definition of the German Society of Gynecology and Obstetrics (DGGG) 314 women had moderate preeclampsia (74.2%), while 109 had severe preeclampsia due to the presence of a blood pressure>170/110 mmHg (n=41; 9.7%), and/or IUGR<5th percentile (n=28; 6.6%), and/or HELLP-Syndrome (n=10; 2.4%), and/or proteinuria≥5 g/24 h (n=30; 7.1%). Age, BMI, smoking, and maternal weight were comparable in the groups, while gestational age at delivery as well as fetal outcome parameter were statistically significant unfavourable in patients with severe preeclampsia. Mean 2nd trimester hemoglobin level were statistically significantly higher in women who developed severe vs. moderate preeclampsia (m=12.75±0.99 g/dL vs. m=12.50±1.05 g/dL; p=0.033). However, in the ROC calculations a hemoglobin value of 12.05 g/dL revealed best sensitivity (78%) and specificity (33.8%) in women with subsequent diagnosis of severe preeclampsia, whereas sensitivity was 100% for a value>10.95 g/dL. There were no statistically significant differences for none of the rheological parameters at the time of delivery between groups of patient with moderate v.s severe preeclampsia. Severe preeclampsia and IUGR, however, was associated with statistically significantly higher RBC aggregation as compared to patients with moderate preeclampsia. Plasma viscosity was statistically significantly (p<0.05) correlated with Fibrinogen values (r=0.16), leukocyte-(r=0.11) and platelets-count (r=0.127), and hemoglobin/hematocrit values in particular (r=0.23/0.26). Although mean 2nd trimester hemoglobin concentration are higher in patients with subsequent development of severe preeclampsia, due to the low sensitivity and specificity of this parameter clinical use for identifying women at risk is of limited value. On the other hand, a hemoglobin value below 11.0 g/dL excluded the risk for severe preeclampsia to 100%. Blood rheological parameters at the time of delivery in the absence of IUGR are not markedly influenced by severity of preeclampsia.

Comparación del método de Johnson-Toshach y la ultra sonografía para estimar el ponderado fetal en gestantes a término asistidas en el Hospital Regional de Cajamarca

Objetivo: Comparar el método de Johnson-Toshach y la ultrasonografía en la estimación del ponderado fetal en gestantes a término. Diseño: Estudio descriptivo, comparativo, prospectivo, longitudinal. Institución: Hospital Regional de Cajamarca, Cajamarca, Perú. Participantes: Gestantes a término. Métodos: A 236 gestantes entre 37 y 41 semanas se midió la altura uterina y según la fórmula de Johnson-Toshach se calculó el ponderado fetal; posteriormente, se realizó una ecografía obstétrica para estimar el ponderado fetal según la fórmula de Hadlock 2. Se esperó un máximo de 48 horas para el parto; luego, se pesó al recién nacido. Se realizó el análisis estadístico en el programa SPSS 19, utilizando las pruebas t student y de McNemar, con un valor p&lt;0,05. Principales medidas de resultados: Peso fetal. Resultados: El promedio del peso fetal estimado por el método de Johnson-Toshach fue más exacto que el calculado por ultrasonografía, con un error relativo de 6,5% versus 8,6% (p=0,001). En fetos macrosómicos, la sensibilidad de la ultrasonografía fue significativamente superior a la del método de Johnson-Toshach (75% versus 62,5%, p=0,013). En fetos con peso normal, el método de Johnson-Toshach fue significativamente más sensible que la ultrasonografía (98% versus 89,3%, p=0,016). En fetos con peso bajo, la ultrasonografía tuvo mejor sensibilidad que el método de Johnson-Toshach (57,8% versus 51,2%), pero la diferencia no fue significativa (p=0,238). Conclusiones: El ponderado fetal estimado por el método de Johnson-Toshach fue más exacto que la ultrasonografía en gestantes entre 37 y 41 semanas de gestación, para fetos con pesos entre 2 501 y 3 999 g.

Estimation of fetal weight before delivery in low-resource setting of North-west Nigeria: can we rely on our clinical skills?

Objective: To compare the accuracy of sonographic versus clinical methods of fetal weight estimation in a low-resource setting.Methods: This was a prospective study. Ethical clearance and informed consent were obtained. Two hundred (200) women admitted for delivery were assessed. Questionnaires and data collection forms were used to obtain socio-demographic and other clinical information. The actual weight was determined at birth. Estimated fetal weight (EFW) was compared with the actual weight (BW). The data obtained were analyzed using SPSS version 16.0 statistical software. The accuracy of clinical and sonographic fetal weight estimation was compared using Students’ t-test, Chi-square test and Pearsons’ coefficient of correlation and p < 0.05 was considered statistically significant.Results: The mean of absolute percentage error was smaller for ultrasonic (9.8 ± 7.2) than clinical (10.5 ± 7.5) estimation, but the difference was not statistically significant (p = 0.083). In the 2.5–3.99 kg group there was no statistically significant difference between the mean absolute percentage errors for the two methods (p = 0.096). In the <2.5 kg group, clinical method overestimated birth-weight while in ≥4.0 kg, the sonographic method underestimated the birth weight. For birth weight 2.5–3.99 kg, sensitivity, specificity, positive predictive value and negative predictive value were 96.9, 76.9, 98.1, 66.7% and 96.8, 75, 96.8, 75% for sonographic and clinical estimates, respectively. The predictive powers of sonographic and clinical methods were better for low birth weight and macrosomic fetuses, respectively.Conclusion: Clinical method of fetal weight estimation can only be recommended for use as screening tool for normal weight and macrosomic fetuses.

Post-partum trend in blood pressure levels, renal function and proteinuria in women with severe preeclampsia and eclampsia in Sub-Saharan Africa: A 6-months cohort study

BackgroundPreeclampsia and eclampsia, which are the most frequent hypertensive disorders in pregnancy, are associated with renal involvements. We aimed to assess the time trend in blood pressure levels, renal function and proteinuria after delivery, and investigate their determinants in Cameroonian women with severe preeclampsia and eclampsia.MethodsThis was a prospective cohort study involving 54 women with severe preeclampsia and eclampsia, conducted between July 2010 and February 2012 at the central maternity unit of the Yaoundé Central Hospital. Clinical and laboratory parameters were recorded from day-1 to 6 months after delivery. Mixed-linear and logistic regression models were used to relate baseline and within follow-up levels of covariates, with changes in blood pressure levels, renal function and proteinuria, as well as persisting hypertension, renal failure and proteinuria.ResultsDuring follow-up, a significant improvement was observed in blood pressure, renal function and proteinuria (all p < 0.002). Thirteen (24.1%) patients with renal failure at delivery recovered completely within six weeks. Twenty-six (48.1%), 17 (31.5%) and 1 (1.8%) patients had persisting proteinuria at 6 weeks, 3 months and 6 months post-delivery, respectively. Corresponding figures for persisting hypertension were 23 (42.6%), 15 (27.8%) and 8 (14.8%). Advanced age, higher body mass index, low gestational age at delivery, low fetal birth weight, and proteinuria at delivery were the main risk factors for persisting hypertension at 3 months, meanwhile low fetal birth weight, severe preeclampsia and proteinuria at delivery were correlated with persisting proteinuria at 3 months. Advanced age and higher body mass index were the only determinants of the composite outcome of persisting hypertension or proteinuria at three and six months.ConclusionHypertension and proteinuria are very common beyond the postpartum period in Cameroonian women with severe preeclampsia and eclampsia. Long-term follow-up of these women will help preventing and controlling related complications.

Altered Expression of miR-518b and miR-519a in the Placenta is Associated with Low Fetal Birth Weight

Previous studies have suggested that the expression and function of placenta-specific microRNAs (miRNAs) are associated with placenta trophoblastic proliferation and invasion. This study investigated whether the altered expression of placenta-specific miRNAs was involved in the development of fetal growth. Placenta tissues were obtained from pregnant women with large for gestational age (LGA), intrauterine growth retardation (IUGR), and appropriate for gestational age (AGA) infants (n = 30 in each group). Real-time quantitative reverse transcription-polymerase chain reaction was used to analyze the expression of relative placenta-specific miRNAs in human placental tissues from three different groups. Compared with the LGA and healthy control (AGA) groups; the expression of miR-518b was decreased, whereas miR-519a was significantly increased in the placentas from the IUGR group (p < 0.05). This study suggests that altered expression of placenta-specific miRNAs (miR-518b and miR-519a) may be involved in the development of IUGR.

Pregnancy and Glycemic Index Outcomes study: effects of low glycemic index compared with conventional dietary advice on selected pregnancy outcomes

Eating carbohydrate foods with a high glycemic index (GI) has been postulated to result in fetoplacental overgrowth and higher infant body fat. A diet with a low glycemic index (LGI) has been shown to reduce birth percentiles and the ponderal index (PI). We investigated whether offering LGI dietary advice at the first antenatal visit would result in a lower fetal birth weight, birth percentile, and PI than providing healthy eating (HE) advice. This advice had to be presented within the resources of routine antenatal care. The Pregnancy and Glycemic Index Outcomes study was a 2-arm, parallel-design, randomized, controlled trial that compared the effects of LGI dietary advice with HE advice on pregnancy outcomes. Eligible volunteers who attended for routine antenatal care at <20 wk of gestation were randomly assigned to either group. A total of 691 women were enrolled, and 576 women had final data considered. In the LGI group, the GI was reduced from a mean (± SEM) of 56 ± 0.3 at enrollment to 52 ± 0.3 (P < 0.001) at the final assessment. There were no significant differences in primary outcomes of fetal birth weight, birth percentile, or PI. In a multivariate regression analysis, the glycemic load was the only significant dietary predictor (P = 0.046) of primary outcomes but explained <1% of all variation. A low-intensity dietary intervention with an LGI diet compared with an HE diet in pregnancy did not result in any significant differences in birth weight, fetal percentile, or PI.

Morphometry Examination of Placenta in Birth Weight of Full-Term Newborns in Puducherry, India

irth weight is an important determinant of child survival, healthy growth and development. Low birth weight is a well-established risk factor for adverse long term health, particularly cardiovascular disease and metabolic syndrome. The ability of the fetus to grow and thrive in utero is presumed to be a function of the placenta. The present study was aimed to assess the morphometry examination of placenta in normal and low birth weight babies in the Union territory of Puducherry. Morphometry examination includes Placenta weight, number of cotyledons, maternal and fetal surface area and site of umbilical cord insertion were measured in normal and low birth weigh babies. Result showed among 200 subjects, mean birth weight of normal and low birth babies were 2806 and 2058 g, respectively. The prevalence rate of low birth babies (less than 2500 g) was 22%. The placental morphometry study namely placental weight, number of cotyledons, maternal and fetal surface area and insertion of umbilical cord at centre were significantly (p<0.001) reduced in the low birth weight babies when compared with normal birth weight babies. Study revealed that morphometry analysis of placenta significantly influences the birth weight of new born. In conclusion, study recommends the early measurements of placenta by non-invasive techniques like ultrasonography will be helpful in early prediction of low birth weight fetus in utero itself and for better management to avoid such low birth weight.

PF.39 Clinical Relevance of Fetal Weight Estimation in Southwest Uganda

BackgroundThere is an increasing incidence of low birth weight babies (<2500 g) in Uganda. This can cause significant perinatal morbidity and mortality and is related to intrauterine growth restriction (IUGR)....

Fetal Outcome of Pre-eclamptic Mothers with Hyperuricemia

Pre-eclampsia (PE) is considered as a major cause of maternal and fetal morbidity and mortality. When a pre-eclamptic woman develops associated hyperuricemia then fetal outcome may become worse. To observe the fetal outcome of hyperuricemic pre-eclamptic pregnancy in relation to normo-uricemic pre-eclamptic pregnancy in a hospital based comparative and cross-sectional study 62 pre-eclamptic patients were selected purposively. PE was diagnosed by hypertension and proteinuria. PE patients were divided into two groups by there serum uric acid level - Hyperuricemic &amp; Normo-uricemic. Then fetal outcome markers (Stillbirth and low birth weight fetus) of the study groups were observed. In this study significant increased number of low birth weight fetuses was observed in babies born to hyperuricemic pre-eclamptic mothers in comparison with babies born to normo-uricemic pre-eclamptic mothers. According to the observation the estimation of serum uric acid may be considered in management of pre-eclamptic mothers, especially in lowering the rate of poor fetal outcome. DOI: http://dx.doi.org/10.3329/jdnmch.v17i1.12192 J. Dhaka National Med. Coll. Hos. 2011; 17 (01): 41-43

Nutrient sensor–mediated programmed nonalcoholic fatty liver disease in low birthweight offspring

We hypothesized that gestationally programmed nonalcoholic fatty liver disease in low-birthweight offspring is mediated through nutrient sensors nicotinamide adenine dinucleotide+-dependent histone deacetylase (SIRT1) and AMP-activated protein kinase (AMPK). Pregnant dams received ad libitum food or were 50% food restricted from pregnancy days 10-21 to produce control and low-birthweight newborn offspring, respectively. All pups were nursed by control dams and weaned to ad libitum feed. We determined hepatic SIRT1 and AMPK activities and protein expression of lipid targets in low-birthweight and control fetuses, newborns, and adult offspring (3 months). Low-birthweight fetuses demonstrated increased prenatal hepatic SIRT1 activity, although with increased lipogenesis. After birth, low-birthweight newborn offspring undergo postnatal suppression of hepatic SIRT1 and AMPK activities in conjunction with increased lipogenesis, decreased lipolysis, and increased fat stores. These findings suggest that undernutrition stress in utero may program hepatic nutrient sensors to perceive normal postnatal nutrition as a state of nutrient excess with the induction of hepatic lipid storage.

First trimester 3D volumetry. Association of the gestational volumes with the birth weight

Objective. To evaluate the three dimensional ultrasound (3D) in the volume assessment of the gestational contents during the 1st trimester of pregnancy. Our aim was to correlate the embryo, gestational sac, and placenta volume with the birth weight. To monitor the increase of these volumes according to the gestational age.Method. Prospective study of 199 singleton low risk pregnant women undergoing the 1st trimester ultrasound for fetal anomalies. In these women, gestational volumetry was performed and it was compared with the crown-rump length (CRL). Regression models were computed in order to analyze the dependence of birth weight with the volumes.Results. The embryo volume reveals the strongest association with the birth weight at delivery (β = 0.24), followed by the CRL (β = 0.20) and the gestational sac volume (β = 0.20). The placenta volume appears the weakest association with fetal weight at delivery (β = 0.16). All volumes increased significantly from 11+0–11+6 to 13+0–13+6 weeks of gestation (p < 0.001). Ten cubic millimeter increase in embryo volume corresponds to a mean birth weight increase of 75 g, while 1 mm increase in the CRL corresponds to a birth weight increase of 113 g.Conclusion. Our results provide evidence that the embryo volume during the first trimester of pregnancy correlates better with birth weight than the CRL. This might assist in the identification of the high risk pregnancies caring macrosomic and low birth weight fetuses.

Weight estimation for low birth weight fetuses and macrosomic fetuses in Chinese population

Compared with normal birth weight fetuses (2,500-4,000 g), accurate fetal weight estimation for fetuses with low or excessive weight is considered more important for fetal compromise prediction and labor management. New formulas were developed to estimate weight for low birth weight (LBW) fetuses and macrosomic fetuses, respectively. A total of 523 fetuses with birth weight less than 2,500 g, 652 fetuses with normal birth weight, and 239 fetuses with birth weight more than 4,000 g were included in the study. As much as 25 existing formulas which incorporate regularly defined fetal measurements were evaluated and compared. Performance evaluation of existing formulas showed that no formulas can provide consistently accurate weight estimation both for LBW fetuses and macrosomic fetuses. A total of 1,034 cases were utilized to generate an overall regression formula. If the pre-estimated weight fell into the suspicious LBW and macrosomia range, the value was then updated by using the new regression formulas for LBW fetuses and macrosomic fetuses. As the training group, 262 LBW fetuses and 120 macrosomic fetuses were employed in a stepwise linear regression to obtain two update regression formulas for suspicious LBW fetuses and macrosomic fetuses. As the validation group, another 261 LBW fetuses and 119 macrosomic fetuses were assessed. The new overall formula has the form of Log(10)BW = 0.180(HC) + 0.00628(AC) - 0.00318(HC)(2) + 0.00173(AC)(FL) + 0.0000430(BPD)(HC)(2). The update formula for suspicious LBW fetuses is LnBW = 1.470(BPD) + 0.0169(HC) - 0.0873(BPD)(2) + 0.00518(AC)(FL) and for macrosomic fetuses is Log(10)BW = 0.730(BPD) - 0.0375(BPD)(2) + 0.000264(AC)(FL). For LBW fetuses, the new method gave 7.6 ± 209.0 (g) of estimation error and 8.3 ± 7.8 (%) of absolute percentage error, while the best existing formula provided -0.7 ± 226.0 (g) and 9.1 ± 8.3 (%). With the new method, 71.3% of estimates fell within ±10% of the actual birth weight, while the best existing formula gave 65.5%. For macrosomic fetuses, the new method gave -87.9 ± 231.0 (g) of estimation error and 4.4 ± 3.9 (%) of absolute percentage error, while the best existing formula provided 115.6 ± 345.1 (g) and 6.8 ± 5.4 (%). With the new method, 89.1% of estimates fell within ±10% of the actual birth weight, while the best existing formula gave 75.6%. To improve the weight estimation accuracy for low or excessive weight fetuses, separate formulas are necessary. The new method provides significant improvement on fetal weight estimation for LBW fetuses and macrosomic fetuses.