AFJOG

African Journal of Obstetrics and Gynaecology | Volume 2 | Issue 3 | 2024 | 26 ORIGINAL RESEARCH African Journal of Obstetrics and Gynaecology | Volume 2 | Issue 3 | 2024 | The role of foot length measurement to determine the gestational age in stillbirths reproducible in any setting, and may be helpful in a low- resource setting. When investigating factors leading to stillbirths, it is crucial to determine the best gestational age at the time of fetal death. Despite wide access to antenatal ultrasound in South Africa, pregnant women often book late for antenatal care, making estimating the gestational age by an ultrasound unreliable. Therefore, foot length measurement could prove to be a reliable, cheap and non- invasive method of estimating a stillborn gestational age in the absence of a reliable dating method. This study investigates the accuracy of using the neonatal foot length to establish the gestational age in stillbirths, compared with EUS, LNMP and SFH. Secondly, to establish if there are any factors relating to stillbirth that might account for the inaccuracy of this method when compared to the gold standard (EUS age ≤24 weeks). METHODS The study was a monocentric prospective, observational descriptive study from August 2017 to August 2018 in the Department of Obstetrics and Gynaecology at Kalafong Provincial Tertiary Hospital (KPTH) situated in Atteridgeville, Pretoria, Gauteng. All stillbirths weighing ≥ 500g that were delivered either by normal vaginal delivery or by caesarean section constituted the study population. All singleton or multiple pregnancies, fresh, or macerated stillbirths weighing ≥ 500g were included in the study irrespective of maternal illness, age, antenatal care or the mode of delivery. Stillbirths with assumed or confirmed genetic abnormalities or physical congenital abnormalities were excluded from the study. Gestational age was classified as either sure or unsure. Sure gestational age is defined by a certain LNMP (sure dates) established from a regular 28- day cycle in a woman who was not breastfeeding or using long-acting contraception, or a dating EUS scan ≤ 24 weeks. Unsure gestational age was any maternal presentation that did not meet the abovementioned criteria in which case the gestational age was determined using the SFHmeasurement. Stillbirths were classified based on appearance as either fresh or macerated. Maceration was defined by any peeling of skin ranging from mild, moderate to severe. Once the fetus was delivered, a standard non-stretchable tape was used to measure the stillborn foot length in millimetres within 1 hour of delivery. The measurement was taken from the centre of the back of the heel to the tip of the big toe. Both feet were measured twice, and the biggest measurement was recorded, along with other routinely measured parameters such as head circumference, length and birth weight. To reduce interobserver bias, a footprint of the foot with the longest measurement was taken. The footprint distance between the tip of the big toe and the centre of the heel was measured by the investigator and compared to the recorded measurement. Only the EUS population was analysed to assess the impact of growth on the gestational age as an EUS is considered the gold standard in determining gestational age. A weight below the 10th percentile equates to intrauterine growth restriction, based on the Fenton preterm growth charts for boys and girls. Whilst a weight greater than the 90th percentile equates to large for gestational age. 15 The EUS population was used to investigate the impact of intrauterine growth restriction on foot length accuracy. Descriptive statistics consisting of summary statistics (i.e. mean, range) for numerical data and frequencies for categorical data were used. Pearson correlation coefficient and the performance of the foot length measurement were evaluated with a Bland Altman plot. The groups were compared using the chi-square test, Fisher’s exact tests, and sample t-tests for proportions. The software used was SPSS. A p-value of <0.05 was considered statistically significant. RESULTS Eighty-two eligible stillborn infants were recruited to the study. Seventy-three women (89%), attended for antenatal care, of which 32 (43.8%) had an EUS, and 41 (56.2%) had no ultrasound despite booking early. The foot length was measured for all the 82 stillbirths. The maternal characteristics are presented in Table 1. The gestational age was determined by an EUS in 32 (39%) stillbirths, sure LNMP in 32 (32%) stillbirths, and SFH in 18 (22%) stillbirths. The stillborn characteristics included in the foot length analysis are presented in Table 2. There were 78 (95.1%) normal deliveries and four (4.9%) caesarean section deliveries. The indications for caesarean delivery were all due to previous caesarean sections. There were 20 (24.4%) fresh stillbirths and 62 (75.6%) macerated stillbirths. Thirty-five (42.7%) stillbirths had a foot length with greater than the acceptable accuracy of less than 2 weeks, of which five of the 35 (14.3%) were fresh stillbirths and 30 (85.7%) were macerated stillbirths. The mean measured foot length and the mean validated measured foot length were 62.2mm and 61.0mm, respectively. The two measurements showed a high correlation to the estimated gestational age (Table 3). The mean gestational age for all women by best estimate (EUS, SD and SFH) was 31.7±5.3 weeks, while the mean gestational age determined by the foot length measurement was 30.9±5.2 weeks; similarly, the two measurements showed a high correlation (Table 4). Table 1. Maternal baseline characteristics Characteristics n*(%) Total (n) 82 Maternal age (y) 28.8±5.9 Gravida 2.6±1.5 Parity 1.2±1.1 Previous miscarriage 0.33± 0.7 Previous stillbirth 2 (2.4) Attended antenatal care 73 (89) Did not attend antenatal care 9 (11) Rhesus negative 2 (2.4) HIV positive 19 (23.2) Anemia 25 (30.5) Syphilis positive 0 (0.0)