Effect of dexamethasone on amniotic fluid absorbance in Rh-sensitized pregnancy

Summary. Five Rh-sensitized pregnant women between 23 and 30 weeks gestation, with a poor obstetric history and initially high Δ A ₄₅₀ values, were treated with weekly doses of 24 mg of dexamethasone over a period of 2–7 weeks to enhance fetal lung maturation. Four women showed a gradual decline in Δ A ₄₅₀ during the treatment. All five deliveries were delayed until fetal lung maturity was confirmed by amniotic fluid lecithin/sphingomyelin (L/S) ratio and all five fetuses survived. It is possible that high doses of dexamethasone delayed the anticipated intrauterine deterioration of the fetuses and may have prevented the need for intrauterine transfusions.     

Fetal liver ultrasound measurements in isoimmunized pregnancies

Sixteen isoimmunized pregnancies at risk for erythroblastosis fetalis were managed by serial amniocenteses for bilirubin delta optical density at 450 nm (delta OD450). Before amniocentesis each fetus was evaluated ultrasonically and the fetal liver size, the abdominal circumference, and the umbilical vein diameter, in both the fetal liver and the umbilical cord, were measured. The ultrasonically determined fetal liver size, as well as its growth rate, was found to be greater than normal during the last two weeks before intervention (intrauterine transfusion or delivery) in all eight fetuses with severe hemolytic disease. The umbilical vein diameter in the fetal liver was above normal in only one fetus, whereas the abdominal circumference was increased in only three of the eight severely affected fetuses. These data suggest that serial fetal liver ultrasound measurements may be useful as an adjunct to amniotic fluid analysis to predict the severely affected fetus in need of prompt intervention (intrauterine transfusion or delivery).     

Sonographic sign for the detection of early fetal ascites in the management of severe isoimmune disease without intrauterine transfusion

Ultrasonography is an important adjunct to the delta optical density at 450 nm in the management of isoimmunized pregnancies. We describe a sonographic finding that we believe is the earliest sign of fetal ascites suggesting decompensation. In this patient, despite high measurements of delta optical density at 450 nm, intrauterine therapy or delivery was delayed for more than 7 weeks by careful sonographic monitoring.     

Single umbilical artery: prenatal findings

In 450 patients with pregnancy at high risk for fetal malformation and/or intrauterine growth retardation, the umbilical cord was investigated sonographically for the presence of a single umbilical artery. A single umbilical artery was diagnosed in four fetuses between 23 and 33 weeks of gestation and suspected in two. Three cases were overlooked at sonography. All seven surviving fetuses had growth retardation at delivery and four also showed severe malformations. Whenever a single umbilical artery is found at sonography, further work-up is required to rule out associated anomalies, intrauterine growth retardation, or chromosomal abnormality.     

The effect of betamethasone and dexamethasone on fetal heart rate patterns and biophysical activities. A prospective randomized trial.

BACKGROUND; Contradictory findings on the effect of betamethasone versus dexamethasone on antenatal tests of fetal well-being have been reported. The purpose of this study was to compare the effects of these steroid compounds on fetal heart rate patterns and biophysical activities in a prospective. randomized trial. STUDY DESIGN: Forty-six pregnant women (gestational age range 27-34 weeks) at risk for preterm delivery were randomized to receive betamethasone or dexamethasone for enhancement of fetal lung maturity. Fetal heart rate was recorded for 60 minutes and analyzed with the Sonicaid System 8000 before (0 hours), and 48 hours and 96 hours after steroid administration. Subsequently, fetal limb, body and breathing movements were sonographically observed and quantified for 30 minutes. To account for fetal circadian rhythms, all examinations were performed between 1 p.m. and 5 p.m., at least one hour after maternal meals. RESULTS: Fetal heart rate accelerations (p<0.001; p<0.01), short-term variation (p<0.0001; p<0.05), long-term variation (p<0.01; p=NS), duration of high episodes (p<0.001; p<0.05), total movement count (p<0.001; p<0.05), and duration of breathing time (p<0.0001; p<0.0001) were substantially reduced 48 h after betamethasone and dexamethasone administration, respectively, with percent reduction being larger for the betamethasone group, except for breathing movements (p<0.05; p<0.001; p<0.001; p<0.005; p<0.05; p=NS; respectively). In 68.2%( and 45.5% of fetuses, less than 30 seconds of continuous breathing movements were found in the betamethasone and dexamethasone groups, respectively. In 71.8% and 12.5%, of fetuses, respectively, less than 2 body/limb movements were observed. Therefore five and two fetuses in the betamethasone and dexamethasone study group, respectively, had both nonreactive fetal heart rate monitors for 60 minutes and biophysical profiles of < or =4/10. All parameters returned to baseline values at 96 h. Baseline fetal heart rate and numbers of decelerations remained unchanged (p=NS). CONCLUSIONS: Both betamethasone and dexamethasone induce a profound, albeit transient, suppression of fetal heart rate characteristics and biophysical activities in the preterm fetus. However, the effect of betamethasone is more pronounced. Awareness of these phenomena might prevent unwarranted iatrogenic delivery of preterm fetuses.     

Effect of dexamethasone and betamethasone on fetal heart rate variability in preterm labour: a randomised study

Objective To compare the effects of betamethasone and dexamethasone on fetal heart rate in appropriately grown fetuses.
Methods Eighty-two pregnant women (97 fetuses) with preterm labour were randomly allocated to receive betamethasone (   n = 42  ) or dexamethasone (   n = 40  ) for fetal lung maturation in a nonblinded fashion. Computerised cardiotocogram (CTG) parameters were compared before, during and after treatment.
Results A decrease in fetal heart rate variability was found with betamethasone but no significant changes were found with dexamethasone. Fetal heart rate variability returned to pre-treatment values within a week after cessation of treatment with betamethasone. Neonatal outcome was similar in the two groups.
Conclusions These findings might prove useful in the management of compromised fetuses with decreased fetal heart rate variability in which the CTG should be used together with other parameters to assess fetal wellbeing during corticosteroid treatment. Dexamethasone may be preferable as the drug of choice since it was associated with significantly less alteration in fetal heart rate variability compared with betamethasone.     

Fetal intravascular transfusion for hydropic disease due to rhesus isoimmunization

OBJECTIVE: To evaluate the management of hydropic fetuses, due to rhesus isoimmunization, with fetal intrauterine intravascular transfusions. MATERIAL AND METHODS: This is a retrospective analysis of 18 rhesus-negative pregnant women presenting at our hospital with fetal hydrops during a 7-year period. All cases were managed with serial intrauterine intravascular transfusions with the goal of delivery by cesarean section beyond 33 weeks of gestation. All patients received prophylactic ampicillin and ritodrine for 4 days after the procedure. RESULTS: There were 11 mildly and 7 severely hydropic fetuses. All fetuses with mild hydrops and 5 of the 7 with severe hydrops were delivered alive after 32 weeks of gestation in a good condition. Two fetuses both with severe hydrops died in utero, at 28 weeks of gestation. Intrauterine reversal of hydrops occurred in 90.9% of fetuses with mild hydrops and in 57.1% of severely hydropic fetuses. CONCLUSIONS: The survival rate for the hydropic fetuses in our study was 88.9% and it was associated with the severity of fetal hydrops.     

Ultrasonographic measurement of fetal femur length in growth disturbances

Ultrasonographic measurement of fetal femur length is a recognized technique for determination of gestational age and fetal growth. A total of 280 pregnant women were studied, each of whom had pathologies with the potential to either accelerate or delay fetal growth. There were 1000 measurements of the fetal femur length performed on these 280 fetuses. A total of 125 fetuses were found to have a growth disturbance-91 with asymmetrical intrauterine growth retardation and 34 with macrosomia. Comparison of fetuses with either intrauterine growth retardation or macrosomia with appropriate-for-gestational-age fetuses showed that the femur length is not statistically affected by intrauterine growth abnormalities.     

Expectant management of severe preterm preeclampsia: is intrauterine growth restriction an indication for immediate delivery?

OBJECTIVE: Expectant management of severe preterm preeclampsia is gaining widespread acceptance in clinical practice. The objective of our study was 2-fold-to determine the frequency of fetal deterioration with expectant management of severe preterm preeclampsia and to evaluate whether the presence of intrauterine growth restriction on admission is associated with a shorter admission-to-delivery interval or more deliveries resulting from nonreassuring fetal status in comparison with pregnancies with preeclampsia but without intrauterine growth restriction. STUDY DESIGN: This was an observational study of women with singleton pregnancies at <34 completed weeks' gestation who were admitted to the hospital with the diagnosis of severe preeclampsia and managed expectantly. Fetal status on admission, admission-to-delivery interval, indication for delivery, and neonatal outcome were examined. RESULTS: Forty-seven women were studied during a 3-year period (1996-1999). Gestational age at admission was 29.8 +/- 2.6 weeks. The mean admission-to-delivery interval for the entire group was 6.0 +/- 5.1 days; in 42.5% delivery was for fetal indications. In comparison with the absence of intrauterine growth restriction, the presence of intrauterine growth restriction at admission resulted in a significantly shorter admission-to-delivery interval (3.1 +/- 2.1 vs 6.6 +/- 6.1 days; P <.05). Most fetuses with intrauterine growth restriction (85.7%) were delivered before 1 week. Although 57% of fetuses with intrauterine growth restriction were delivered for fetal indications, versus 39% of fetuses without intrauterine growth restriction, these rates were not found to be significantly different. Neonatal outcomes, as reflected by Apgar scores, number of admissions to and duration of stay in the neonatal intensive care unit, and neonatal mortality rates, were similar. CONCLUSION: Pregnancies complicated by severe preterm preeclampsia and the presence of intrauterine growth restriction at admission may not benefit from expectant management beyond the 48 hours needed for betamethasone to act. Furthermore, all patients may benefit from close fetal monitoring before delivery because of the high rate of intervention for deteriorating fetal status.     

The fetus with gastroschisis managed by a trial of labor: antepartum and intrapartum complications.

OBJECTIVE: To assess the rate of antepartum and intrapartum complications of fetuses with antenatally diagnosed gastroschisis managed in a center that advocates a trial of labor. STUDY DESIGN: A retrospective review. The medical records of 49 fetuses (1988 to 1997) who were prenatally diagnosed with gastroschisis by a sonologist in the Ultrasound Genetic Unit, Department of Obstetrics and Gynecology at Washington University, were reviewed. RESULTS: Oligohydramnios and intrauterine growth restriction were diagnosed in 23% and 49% of the pregnancies, respectively. A total of 22 women underwent induction of labor nine for nonreassuring fetal testing, four for premature rupture of membranes, five for marked bowel dilatation, one for preeclampsia, and three for other reasons. Cesarean section (CS) was performed in 16 of 43 (37%) of women. The indications for CS were fetal distress (9 of 16 women), chorioamnionitis (2 of 16 women), breech presentation (3 of 16 women), and physician discretion (2 of 16 women). No significant differences in Apgar scores were observed between the fetuses. Fetuses who were delivered by CS for fetal distress were more likely to have undergone an induction of labor (91% versus 44%), and they were smaller than fetuses with no evidence of fetal distress (2220 +/- 105 gm versus 2613 +/- 80 gm, p < 0.05). CONCLUSION: The incidence of antepartum and intrapartum complications in fetuses with gastroschisis is high. The rate of CS can reach 37%. These data may aid clinicians in counseling patients with gastroschisis.     

Factors associated with fetal demise in fetal echogenic bowel.

OBJECTIVE: The purpose of this study was to determine risk factors associated with intrauterine fetal demise in fetuses with unexplained echogenic bowel that is diagnosed in the second trimester. STUDY DESIGN: A retrospective case-control study compared fetuses with echogenic bowel and fetal demise with fetuses with echogenic bowel who were live born. Fetuses affected with cystic fibrosis, aneuploidy, or congenital infection and fetuses diagnosed with major anomalies were excluded. Variables examined in the determination of risk factors for intrauterine fetal demise included intrauterine growth restriction, oligohydramnios, elevated maternal serum alpha-fetoprotein levels, and elevated maternal serum beta-hCG levels. Statistical analysis was performed with the Fisher exact test, Student t test, and logistic regression analysis. RESULTS: One hundred fifty-six fetuses met the inclusion criteria. There were 9 cases of intrauterine fetal demise and 147 live born control fetuses. The median gestational age of intrauterine fetal demise was 22.0 weeks (range, 17-39 weeks). Intrauterine growth restriction occurred more frequently in cases of intrauterine fetal demise than in live born infants (22.2% vs 0.7%; P =.009), as did oligohydramnios (44.4% vs 2.0%; P <.001) and elevated maternal serum alpha-fetoprotein levels (80.0% vs 7.7%; P: =.001). With the use of logistic regression analysis, elevated maternal serum alpha-fetoprotein was the strongest independent risk factor that was associated with intrauterine fetal demise (odds ratio, 39.48; 95% CI, 11.04%-141.25%). CONCLUSION: In our series, there was a 5.8% incidence of intrauterine fetal demise in fetuses with unexplained echogenic bowel. Elevated maternal serum alpha-fetoprotein is the strongest predictor of fetal demise in fetal echogenic bowel.     

Serum and glucocorticoid-inducible kinase in pulmonary tissue of preterm fetuses exposed to chorioamnionitis

OBJECTIVES: The interaction between inflammation and transepithelial Na(+) transport is poorly understood. Chorioamnionitis has been shown to be associated with preterm labor and postnatal pulmonary morbidity of preterm infants. The human isoform of serum and glucocorticoid-inducible kinase (SGK1) is upregulated by proinflammatory cytokines and stimulates epithelial Na(+) channel ENaC and the Na(+)/K(+)-ATPase activity, an effect presumably participating in the regulation of transepithelial Na(+) transport. STUDY DESIGN: Lung tissue sections from 31 stillborn fetuses (range 21-41 weeks of gestational age) with or without chorioamnionitis were analyzed. Macrophages, neutrophils and lymphocytes were stained immunohistochemically. In addition, in situ hybridization for the detection of SGK1 mRNA was performed in fetal lung tissue. Positively labeled cells were compared by semiquantitative assessment. RESULTS: A marked influx of macrophages into the pulmonary tissue of fetuses exposed to intrauterine inflammation when compared to fetuses without exposure to chorioamnionitis was observed (p < 0.05). There was also a tendency towards an increased density of neutrophils in fetuses exposed to chorioamnionitis. However, only small numbers of lymphocytes were detected in both groups. In fetuses exposed to chorioamnionitis, 6 of 8 fetuses did not express SGK1; however, in the group of fetuses without exposure to intrauterine inflammation 15 of 23 cases exhibited a profound SGK1 detection rate in lung tissue and airway epithelium, independent of the gestational age of the fetuses (p < 0.05). CONCLUSIONS: Human serine threonine kinase SGK1 mRNA is observed in fetal lung tissue. On the basis of this study, we speculate that exposure to chorioamnionitis is associated with a downregulation of SGK1 in fetal lung tissue. The possible consequences of a decreased rate of SGK1 mRNA could be an impaired ability to clear the lungs from excessive fluid immediately after preterm birth.     

Intrauterine growth restriction is accompanied by decreased renal volume in the human fetus

OBJECTIVE: Intrauterine growth-restricted fetuses are at risk for the development of adult hypertension and related cardiovascular diseases. Congenital oligonephropathy has been postulated as the primary mechanism. The objective of our study was to determine whether ultrasonically obtained in utero measurements of renal volume or renal artery Doppler blood flow differ between fetuses that are intrauterine growth restricted and fetuses that are not. STUDY DESIGN: The study population consisted of women who were referred for a prenatal ultrasound evaluation at a large community medical center. The women were divided into two groups: women with fetal biometry that was consistent with intrauterine growth restriction and women with biometry within normal range. Information was collected on maternal demographics and other factors known to affect fetal growth. We performed detailed fetal renal anthropomorphic and Doppler blood flow measurements in addition to standard fetal biometric measurements on all patients, specifically comparing renal volume and renal artery flow data between the two groups. RESULTS: No differences were observed in maternal age, race, parity, or fetal gestational age. Renal volume in the intrauterine growth-restricted fetuses was 31% (95% CI, 20%-40%), which was less than that in the group of fetuses that were not intrauterine growth restricted after an adjustment was made for gestational age. The ratio of renal volume to estimated fetal weight was 15% (95% CI, 1%-26%), which was less than the same ratio in the fetuses that were not intrauterine growth restricted. There were no differences seen in the renal artery Doppler measurements. CONCLUSION: Intrauterine growth restriction appears to be associated with a decrease in fetal renal volume. Because renal volume is a likely proxy for nephron number, this study supports the hypothesis that intrauterine growth restriction may be linked to congenital oligonephropathy and potentially to hypertension in later life.     

First-trimester and early second-trimester diagnosis of nuchal cystic hygroma by transvaginal sonography: diverse prognosis of the septated from the nonseptated lesion

Fetal cystic hygroma is a congenital malformation of the lymphatic system appearing as a single or multiloculated fluid-filled cavity, most often in the nuchal region. The malformation is believed to arise from failure of the lymphatic system to communicate with the venous nuchal system. Sometimes the lesion progresses to fetal hydrops, causing fetal death. To further delineate the cause and natural history of this disorder, we have prospectively studied eight cases of cystic hygroma of the neck, detected at gestational ages of 9 to 15 weeks by transvaginal sonography. Three of the eight fetuses survived (37.5%) and were normal at birth. Either hydrops fetalis or intrauterine fetal death occurred in the other five fetuses. In one of these five, therapeutic abortion was induced because of trisomy 21. In another fetus of these five, trisomy 18 was diagnosed by amniocentesis. This pregnancy ended in intrauterine fetal death. The ultrasonic evaluation of the cystic hygromas revealed that those that were reabsorbed in the three ultimately normal viable fetuses were nonseptated cysts, whereas all the four cystic hygromas ending in fetal death or associated with aneuploidy were septated, multilocular hygromas. In another fetus with nonseptated hygroma, nonimmune hydrops developed, which resulted in premature delivery and early neonatal death.     

Analysis of pulmonary venous blood flow in growth retarded fetuses above 30 weeks of gestation

Abnormal spectra of blood flow are observed in many fetal vessels in pregnancy complicated by intrauterine growth restriction. Redistribution of blood flow to the most important organs causes a diminished perfusion of the others. The disturbances of lung perfusion in utero are related to abnormal growth and development of the fetal lung. The aim of this study was to describe blood flow velocity waveforms in fetal pulmonary veins in normally grown and growth restricted fetuses above 30 weeks of gestation. Doppler studies were performed in 53 normally grown and 39 growth restricted fetuses. The subjects of analysis were: peak systolic (VS), peak diastolic (VD), end-diastolic (VA), and pulsatility index for veins (PIV). Analysis was performed for two gestational intervals: 31-36, 37-41 wks. The pulmonary venous flow in growth retarded fetuses demonstrates the similar pattern to that observed in normally grown fetuses above 30 weeks of gestation. There were no statistically significant differences between normally grown and growth restricted fetuses in all analyzed indices in both gestational intervals.     

Ultrasound contributions to the management of the severely isoimmunized fetus

Twenty-four out of 81 fetuses affected by anti-D isoimmunization underwent ultrasonic guided intrauterine transfusions (2.8 I. U. T.s per fetus). The absolute value and trend of delta OD 450 micron value was correlated with the severity of fetal condition as evaluated by ultrasonography following simple semiquantitative grading of ascites (mild, moderate, severe) and diagnosis of hydrops. The evaluation of disease was monitored in this way during transfusion therapy. Transfusion procedures have been ultrasonically guided. When ascites was present a few milliliters of isolytic solution allowed the bubbling effect to be observed. In the case of no ascites we confirmed the needle positioning by a cineradiographic sequence lasting a few seconds. Fetal transfusions were repeated every 10 to 15 days and the amount of packed red cells to be injected was determined according to the week of gestation. Post-transfusion monitoring included ultrasonic reevaluation of fetal parameters and non-stress testing. All fetuses were delivered via cesarean section before the 35th week of gestation. In no case was treatment started after the 31st week. Seventeen fetuses were transfused before the 26th week (71%). In 13 fetuses transfusions were started before ascites had appeared. Only 5 fetuses worsened and the 3 which became hydropic eventually died. The delta OD-450 value of these 5 cases before therapy had already indicated that they were more severely affected. Survival rate in this group was 69%. Eleven fetuses showed different degrees of ascites or hydrops at the time of the first transfusion.(ABSTRACT TRUNCATED AT 250 WORDS)     

超声诊断胎儿肺发育不良的临床价值

目的 探讨多个超声指标用于产前诊断胎儿肺发育不良的临床价值.方法 应用彩色多普勒超声诊断仪,检查271例正常胎儿,建立5个超声指标(肺面积、肺面积与胎儿质量比、胸围与腹围比、肺面积与胸廓面积比、肺面积与头围比)的正常值范围,以低于正常范围二倍标准差为肺发育不良胎儿判断标准.通过对30例肺发育不良高危胎儿的研究,并与尸体解剖及追踪结果对照,比较各超声指标的临床价值.结果 肺面积及肺面积与头围比随孕周增加而增加,肺面积与胎儿质量比随孕周增加而减少,胸围与腹围比、肺面积与胸廓面积比随孕周增加变化较小.肺面积、肺面积与胎儿质量比、胸围与腹围比、肺面积与胸廓面积比、肺面积与头围比用于产前诊断胎儿肺发育不良的准确率分别为83%、97%、50%、70%、87%.肺面积与胎儿质量比诊断准确率最高,灵敏度为95%(20/21),特异度为9/9,阳性预测值为100%(20/20).结论 肺面积与胎儿质量比能较好地预测致死性肺发育不良,具有临床实用性.     

Serial in utero ultrasonographic measurements of the fetal thyroid: a new complementary tool in the management of maternal hyperthyroidism in pregnancy

OBJECTIVE: Treatment of maternal hyperthyroidism during pregnancy is complicated by the lack of readily available measures of the thyroid status of the fetus. The aim of this study is to describe the use of serial in utero ultrasound measurements of fetal thyroid in patients being treated for Graves' disease in pregnancy. METHODS: Over a 24-month period, all pregnant women with Graves' disease attending our special Fetal Thyroid Unit were followed. Maternal thyroid status was assessed by thyroid function tests. Fetal thyroid size was measured serially by transvaginal ultrasonography between 14 and 17 weeks of gestation and by abdominal ultrasonography between 18 and 37 weeks of gestation in 20 women with Grave's disease. RESULTS: In 15 fetuses, thyroid width and circumference were within the 95% confidence interval of the normal population. In five fetuses, thyroid size was above the 95th percentile for gestational age. In three of them, thyroid size decreased concurrently with a decrease in maternal thionamide dosage, reaching normal range. These three fetuses were born euthyroid. In two fetuses, thyroid size was unaffected by a decrement in maternal drug dosage. Both had neonatal thyrotoxicosis at birth. CONCLUSIONS: Serial in utero ultrasonography measuring fetal thyroid size in mothers with Graves' disease can serve as an effective noninvasive tool for the early detection of enlarged fetal thyroid. These findings can be used to monitor the maternal antithyroid drug dosage, thereby preventing intrauterine hypothyroidism in some cases. When a dosage reduction does not cause a decrease in fetal thyroid size, transplacental passage of thyroid-stimulating antibodies causing fetal thyrotoxicosis should be suspected.     

Intrauterine therapy and outcome in four pregnancies of one mother with anti ro-autoantibody positive Sjoegren's syndrome

Autoantibodies against 52/60kD-Ro proteins, frequently present in patients with Sjoegren's Syndrome or systemic lupus erythematosus, are transmitted to the fetus during pregnancy. These autoantibodies can damage the cardiac conductive system of the fetus and cause a complete atrioventricular block, with a mortality of 30 %. We report the intrauterine therapy during four pregnancies of the same mother with high 52/60kD-Ro autoantibodies and the outcome of her infants. Our patient with primary Sjoegren's Syndrome suffered an early miscarriage during her first pregnancy. During the second pregnancy, a fetal atrioventricular block was observed at 23 weeks of gestation. Although subsequently dexamethasone therapy and daily plasmaphereses were started, a cesarean section was necessary at 26 weeks due to hydrops fetalis. The girl died from the atrioventricular block after two days. During the third and fourth pregnancies, dexamethasone therapy was begun already at 7 weeks, and regular plasmaphereses at 15 weeks. The children were delivered by cesarean section at 32 and 36 weeks because of growth retardation. Both had normal electrocardiograms after birth and after 2 and 4 years. In pregnant women with connective tissue diseases, monitoring of anti Ro-autoantibodies and fetal heart function is important. Intrauterine therapeutic options are dexamethasone therapy to suppress maternal and fetal inflammatory reactions and repeated plasmaphereses to reduce autoantibody levels. Postnatal follow up of the infants for atrioventricular block and rheumatic manifestations is necessary.     

Midpregnancy plasma zinc in normal and growth retarded fetuses--a preliminary study.

OBJECTIVE: To determine plasma zinc concentrations in normally and abnormally growing fetuses. DESIGN: Prospective observational study. SETTING: Fetal Medicine Unit, Queen Charlotte's Maternity Hospital. SUBJECTS: 53 pregnant women attending for fetal blood sampling at between 18 and 40 weeks gestation. 27 fetuses were normal (central group), 11 fetuses were growth retarded and 15 were malformed. MAIN OUTCOME MEASURES: Plasma zinc concentrations in maternal and fetal blood at time of fetal blood sampling. RESULTS: In normally growing fetuses, between 18 and 40 weeks gestation, there was no fall in maternal plasma zinc concentration; the fetal level fell by 36%. In 10 fetuses with symmetrical growth retardation, plasma zinc concentration tended to be low, but was not significantly different from that in the normal control fetuses. CONCLUSION: The results suggest that (i) placental transfer of zinc is an uphill secretory process and that it is a rate-limiting step in the accumulation of zinc by the fetus and (ii) in fetuses with symmetrical intrauterine growth retardation, a low plasma zinc is probably a parallel phenomenon and not necessarily an aetiological factor.