P-760 Monozygotic twin rate among IVF centers: A multicenter analysis of data from 18 Italian units

Study question

Could factors inherent to individual centers, related to local clinical or laboratory variables, play a role in the increased incidence of monozygotic twins in IVF?

Summary answer

The rate of MZT did not significantly vary among IVF centers

What is known already

The risk of monozygotic twins (MZT) is increased in couples undergoing in vitro fertilization (IVF). Several systematic reviews have investigated the possible determinants linked to IVF, but results obtained have been inconclusive. Associations have been identified with the prolonged culture at blastocyst stage and young female age. Conventional IVF compared to ICSI, and assisted hatching emerged as possible additional risk factors, but evidence is controversial. Meta-analyses, however, cannot provide robust evidence because of the difficulty in performing multivariate analyses. Moreover, available investigations were retrospective and involved relatively small sample sizes hampering the quality of the collected data.

Study design, size, duration

This is a multicenter retrospective cohort study using the Italian ART National Registry database and involving the Centers reporting data from individual IVF cycles from 2015 to 2019. Eighteen IVF centers were included with a total of 87,076 IVF cycles reported during the study period. The primary aim of the study was to investigate whether the incidence of MZT differed among centers.

Participants/materials, setting, methods

Only single embryo transfer cycles were considered. Women who had sex-discordant twin deliveries were excluded. MZT rate was calculated as the number of multiple pregnancies out of the total number of clinical pregnancies. A binomial distribution model was used to determine the 95% CI of the frequency of MZT. The rates among centers were deemed heterogeneous if the 95% CI in at least one center did not include the mean MZT rate.

Main results and the role of chance

Ten centers reported data from 2015 to 2019, eight from 2017 to 2019. An analysis of the main characteristics of the centers revealed considerable variability. The total number of clinical pregnancies fulfilling our inclusion criteria were 10,440. Of these, 7 were found to be twin pregnancies with discordant gender and were excluded, leaving 10,433 for data analyses. The number of cases included per center varied between 11 and 2,823. Overall, 162 pregnancies were found to be multiple: 48 ended in a miscarriage, 28 spontaneously reduced to singletons and 86 women delivered two or more newborns. The vast majority were twins (n = 160), one was triplet, and one was quadruplet. Considering the denominator of 10,433 pregnancies, the rate of MZT was thus 1.5% (95%CI: 1.3 - 1.8%). The MZT rate among centers varied between 0% (95%CI: 0.0 - 25.9%) and 3.2% (95%CI: 1.3 - 8.1%). All the 95%CIs of the rates of MZT include the 1.5% common rate, thus rejecting the hypothesis that this incidence significantly differed among centers. Spearman correlations between the rate of MZT and variables associated with individual center policies could not identify any significant association. Even when restricting the analyses only to the largest centers, no association emerged.

Limitations, reasons for caution

Our study was limited by its retrospective nature. Furthermore, some centers provided less than 100 cases for data analysis and were therefore poorly informative. External confirmation from larger registries is therefore required.

Wider implications of the findings

This study provides evidences that the rate of MZT did not differ among IVF centers. Furthermore, no clinical and laboratory variables inherent to individual centers were identified in the determinism of IVF-associated MZT. Further studies are needed to identify the causes of increased risk of MZT in IVF practice.

Trial registration number

not applicable

P-034 Rate of testicular histology failure in predicting successful testicular sperm extraction in Non-Obstructive Azoospermia

Study question

Does testicular histology predict successful or unsuccessful TEsticular Sperm Extraction (TESE) in Non-Obstructive Azoospermia (NOA) patients?

Summary answer

Testicular histology failed to predict successful TESE in 1 of 3 NOA patients.

What is known already

The management of patients with Non-Obstructive Azoospermia (NOA) involves TEsticular Sperm Extraction (TESE) combined with IntraCytoplasmic Sperm Injection (ICSI). Sperm retrieval is successful in up to 50% of men with NOA; however, there is no single clinical finding or investigation that can accurately predict a positive outcome. Previous studies have concluded that testicular histology is the best predictor of a successful or unsuccessful TESE.

Study design, size, duration

This is a retrospective study of 525 patients who underwent TESE between January 2018 and December 2020 in Humanitas Fertility Center.

Participants/materials, setting, methods

The cohort was dived in five groups: 287 NOA, 95 necrozoospermia, 18 anejaculation, 1 testicular trauma and 124 Obstructive Azoospermia (OA) patients.

Main results and the role of chance

Sperm was retrieved and cryopreserved in 218/287 patients with NOA (75,95%), 55/95 in necrozoospermia (57,89%), 18/18 anejaculation (100%), 1/1 testicular trauma (100%) and 120/124 in OA patients (96,77%). Interesting that, when we compare sperm recovery data through TESE with the histological assessment (HA) of corresponding testicular biopsy, we found discordance against HA. In particular we retrieved spermatozoa in 218 NOA patients but in 74 of them HA failed to detect them (33,94%). Moreover HA failed to detect spermatozoa in 8/55 (14,54%) in case of necrozoospermia, 1/18 (5,55%) in anejaculation and 10/120 (8,33%) in OA patients.

Limitations, reasons for caution

Testis's heterogeneity is a limitation of the study.

Wider implications of the findings

We found a discordance when HA is compared with sperm recovery data of corresponding testicular biopsy. This data suggest that in case of testicular diagnostics histology in 33,94% of NOA cases there is a wrong diagnosis and 1 of 3 patients it doesn’t retrieve and cryopreserve spermatozoa when it could.

Trial registration number

N A

Power spectral analysis of the heart rate of the human fetus at 26 and 36 weeks of gestation

The fetal electrocardiogram (ECG) was recorded from the maternal abdomen together with sonographic detection of fetal states in four pregnant patients at 26 and 36 weeks of gestation. Computerised algorithms obtained a good recognition of maternal ECG and fetal ECG. The corresponding power spectral density (PSD) was estimated during epochs of quiet or breathing movements for 256 consecutive heart beats. At 36 weeks of gestation the PSD analysis showed heart rate variability components similar to an adult heart. A low frequency component was observed together with a high frequency component in the range of fetal breathing movements. This high frequency component (0.6 - 0.9 Hz) disappeared from the PSD analysis during epochs of apnea. To our knowledge this is the first demonstration of such a mechanism in the human fetus in utero. At 26 weeks no respiratory component was observed in the PSD analysis. The maturation of control mechanisms could be responsible for this difference.