Should spontaneous and medically indicated preterm births be separated for studying aetiology?

An increasing proportion of preterm births result from medical interventions, and the practice of aggregating all preterm births vs. splitting into spontaneous and medically indicated preterm births is inconsistent. While mechanistic and clinical arguments can be offered for either approach, we empirically evaluated the predictiveness of a range of risk factors for preterm birth in the Pregnancy, Infection, and Nutrition Study. Most influences were shared across the two subsets - African-American ethnicity, advancing age, delivery at a university medical centre, prior preterm birth and smoking. Medically indicated preterm births appeared to be associated with intensity of medical care, higher in the university medical centre and lower for the poorest women. Body mass index was positively associated with medically indicated preterm birth and inversely with spontaneous preterm birth. Given the complexity of the aetiological pathways, both aggregation and disaggregation are well justified and should be included in studies of the causes of preterm birth.

Hypoechogenicity of fetal long bones: a new ultrasound marker for arthrogryposis.

OBJECTIVE: To demonstrate osteopenia associated with arthrogryposis. METHODS & RESULTS: We describe 3 cases of fetal arthrogryposis seen prenatally with the sonographic feature of severe hypoechogenicity of the long bones. This manifestation of presumed osteopenia is thought to represent osteoporosis secondary with absent fetal movement. CONCLUSION: We describe hypoechogenicity of the fetal bones as a new sonographic feature of arthrogryposis.

Noninvasive diagnosis by Doppler ultrasonography of fetal anemia resulting from parvovirus infection.

OBJECTIVE: The purpose of this study was to evaluate the feasibility of the middle cerebral artery peak systolic velocity for the detection of fetal anemia in pregnancies that are complicated by parvovirus B19 infection. STUDY DESIGN: Doppler measurements of the middle cerebral artery peak systolic velocity were performed weekly in 32 fetuses at risk for anemia because of maternal parvovirus infection documented by the presence of serum immunoglobulin M antibody. The values of the middle cerebral artery peak systolic velocity and hemoglobin were expressed as multiples of the median. These values were plotted on reference ranges that had been established previously. A cordocentesis was performed either because of fetal ascites or when the middle cerebral artery peak systolic velocity values suggested anemia (middle cerebral artery peak systolic velocity, >1.50 multiples of the median). RESULTS: Gestational age at study entry ranged from 15.1 to 37 weeks. There were 17 fetuses with middle cerebral artery peak systolic velocity of >1.50 MoM (group 1). Sixteen cordocenteses were performed in these fetuses. All 16 fetuses were anemic (15 severely and 1 mildly). Thirteen fetuses had signs of hydrops (12 with severe and 1 with mild anemia). Group 2 included 15 fetuses with the middle cerebral artery peak systolic velocity values <1.50 MoM. Two cordocenteses were performed. One fetus was mildly anemic; the second fetus was not anemic. The remaining 13 fetuses of this group did not have any complications and were not anemic at birth. The sensitivity of the middle cerebral artery peak systolic velocity (>1.50 MoM) for the prediction of anemia because of parvovirus infection was 94.1%; the specificity was 93.3 %; the positive and negative predictive values were 94.1% and 93.3%, respectively. CONCLUSION: Fetal anemia caused by parvovirus infection can be detected noninvasively by Doppler ultrasonography on the basis of an increase in the peak velocity of systolic blood flow in the middle cerebral artery.