title: Fetal cardiac axis in non-anomalous pregnancies: does fetal gender or maternal body mass index (BMI) matter?
abstract: OBJECTIVE
  To determine if cardiac axis obtained at an early ultrasound study (11-15 weeks) differs from that obtained at a late ultrasound study (18-22 weeks) in the same fetus and to evaluate the impact of fetal gender and/or maternal body mass index (BMI).
  
  
  METHODS
  Cardiac axes of 324 non-anomalous fetuses at 11-15 weeks gestation were measured, with follow-up measurements obtained at 18-22 weeks. Comparisons were performed based on gestational age period, fetal gender and obese/non-obese maternal status.
  
  
  RESULTS
  (1) Mean fetal cardiac axis did not change between 11 and 15 weeks; p = 0.8, (2) mean fetal cardiac axis was more levorotated at 11-15 weeks than measurements obtained at 18-22 weeks; 48.1 ± 7.1° versus 43.7 ± 8.9°; p < 0.0001, (3) male fetuses had less levorotated cardiac axis than female fetuses in late ultrasound studies but there was no difference between them at early ultrasound studies; 18-22 weeks male fetus, 42.7 ± 9.3° versus female fetus, 45.2 ± 8.3°; p = 0.02 and 11-15 weeks male fetus, 48.1 ± 7.0° versus female fetus, 48.4 ± 7.4°, p = 0.7, respectively, and (4) similar trends with the overall study population were observed in the comparison between fetuses of obese and non-obese women.
  
  
  CONCLUSIONS
  Fetal cardiac axis remains stable at 11-15 weeks, becoming less levorotated at 18-22 weeks. This may be attributed to increments in fetal lung volume. The differences in cardiac axis measurements between male and female fetuses examined at 18-22 weeks may also be attributable to differences in increment of fetal lung volume during this gestational age period.
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Hutzel Women's Hospital, Detroit Medical Center, Wayne State University School of Medicine , Detroit , MI , USA .
authors.forename: Henry
authors.initials: H
authors.lastname: Adekola
authors.affiliation: b Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , University of Texas Health Science Center at Houston , Houston , TX , USA , and.
authors.forename: Eleazar
authors.initials: E
authors.lastname: Soto
authors.affiliation: c C.S. Mott Center for Human Growth and Development, Wayne State University School of Medicine , Detroit , MI , USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Dai
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Hutzel Women's Hospital, Detroit Medical Center, Wayne State University School of Medicine , Detroit , MI , USA .
authors.forename: Karoline
authors.initials: K
authors.lastname: Puder
authors.affiliation: a Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology , Hutzel Women's Hospital, Detroit Medical Center, Wayne State University School of Medicine , Detroit , MI , USA .
authors.forename: Jacques S
authors.initials: JS
authors.lastname: Abramowicz
mesh_terms: D015992:Body Mass Index; D005260:Female; D047109:Fetal Development; D005318:Fetal Heart / Q000000981:diagnostic imaging* / Q000502:physiology; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000196:embryology; D008297:Male; D009929:Organ Size; D011247:Pregnancy; D012737:Sex Factors; D016216:Ultrasonography, Prenatal
keywords: Early ultrasound study; fetal lung volume; late ultrasound study