Reference values of fetal ultrasound biometry: results of a prospective cohort study in Lithuania.

PURPOSE: The aim of the study was to construct a reference range for the Lithuanian population for fetal biparietal diameter (BPD), occipitofrontal diameter (OFD), head circumference (HC), abdominal circumference (AC) and femur length (FL) and to compare them with the old local and current international reference values. METHODS: A prospective cross-sectional study was carried out in secondary referral centres Vilnius University Hospital Santariskiu Klinikos Centro Affiliate in 2008-2009 and Vilnius Maternity Hospital in 2009-2014. The fetal biometry of 556 fetuses between 12 and 42 weeks gestation was performed. BPD, OFD, HC, AC and FL were measured. The data were collected and the analysis was performed using statistical programs MS Excel, SPSS and Matlab. Different regression models were fitted to calculate the mean and standard deviation at each gestational age for each parameter. RESULTS: The biometric measurements of HC, BPD, OFD as well as AC and FL were performed for 556 fetuses. The centile charts, tables and regression formulae of the biometric parameters were constructed. The comparison of the current charts with those of other two studies revealed no significant differences of HC centiles. AC values were similar to those presented in the international study INTERGROWTH-21 and significantly higher in comparison to the study for the Lithuanian population conducted by Alisauskas (1980). FL values, especially in late pregnancy, were significantly smaller in the INTERGROWTH-21 study compared to our charts; however, there were no significant differences of the 50th centile compared to the results from Alisauskas. CONCLUSIONS: We have constructed and presented centile charts, tables and regression formulae for fetal biometry for the Lithuanian population and compared them with the results of two other studies. The significant differences between our centile charts and those from INTERGROWTH-21 imply the necessity to have local standards of fetal biometry, while the differences of our results from the older study in the same population show the importance of updating fetal biometry reference charts for every generation.

Influence of newborn head circumference and birth weight on the delivery mode of primipara: what is more important?

Objectives Aim of the study was to analyze the impact of head circumference (HC) and birth weight (BW) on the delivery mode and delivery outcomes. Methods Study population consisted of pregnancy, delivery and newborn data from 1,762 women, who delivered between 2004 and 2016 at University Hospital of Zurich (UHZ). Odds ratio (OR) with 95% confidence intervals (CI) were calculated for mode of delivery. Newborns were sorted into four groups according HC or BW. To evaluate the association between HC and delivery outcome, a descriptive analysis was performed. In addition reference charts of newborn HC at term were constructed. Results OR for instrumental delivery (ID) was 2.37 (CI 95%, 1.63-3.46), for C-Section (CS) 3.74 (CI 95%, 1.49-9.37) when HC >36 cm. OR for ID was 1.59 (CI 95%, 1.02-2.50), for CS 3.18 (CI 95% 1.08-9.350) when BW was >4,000 g. OR for ID was 2.15 (95% CI, 1.69-2.73), for CS 1.93 (95% CI, 0.89-4.18) when HC ≥36 cm and BW <4000 g. OR for ID was 2.23 (95% CI, 1.35-3.67), for CS 4.39 (95% CI, 1.48-12.99) when HC ≥36 cm and BW ≥4,000 g. HC ≥36 cm was defined as large in our study. Mothers with higher age and body mass index delivered babies with larger HC (p<0.05). Blood loss and duration of expulsion period and BW was associated with larger HC (p<0.05). Conclusions The rate of ID and CS increased in case of a larger HC and greater BW. However, the main prognostic factor for ID was size of HC: ≥36 cm, but not macrosomia.