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The health risks associated with transferring embryos classified as mosaic by preimplantation genetic testing for aneuploidies (PGT-A) are currently unknown. Such embryos produce PGT-A results indicating the presence of both euploid and aneuploid cells and have historically been deselected from transfer and grouped with uniformly aneuploid embryos as 'abnormal'. In recent years, numerous groups have reported the intentional transfer of mosaic embryos in the absence of uniformly euploid embryos, largely observing births of seemingly healthy babies. However, it remains to be understood whether the embryonic mosaicism invariably becomes resolved during the ensuing pregnancy, or whether the placenta and/or fetal tissues retain aneuploid cells, and if so to what potential clinical effect. Here, we report two cases of mosaicism persisting from the embryonic stage to the established pregnancy. Case 1 involved an embryonic low-level segmental mosaic loss in Chromosome (Chr) 1, which was confirmed in amniocentesis as well as in brain tissue of the products of conception. This pregnancy was terminated due to the chromosomal pathologies associated with 1p36 deletion syndrome, such as severe intellectual disability. Case 2 involved a low-level mosaic Chr 21 trisomy, which was confirmed with chorionic villus sampling and amniocentesis. The ensuing pregnancy was terminated after ultrasound identification of severe abnormalities in the placenta and fetus. Together, these two cases should be taken into account for risk-benefit assessments of prospective mosaic embryo transfers., (© The Author(s) 2023. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Over a 4 year period ending 1 January 1995, 51 women scheduled for in-vitro fertilization (IVF) and embryo transfer were inadvertently severely overstimulated with menotrophins, as evidenced by the development of > 29 ovarian follicles in association with peak plasma oestradiol concentrations of > 6000 pg/ml. Accordingly, these women were at great risk of developing life-endangering complications associated with severe ovarian hyperstimulation syndrome (OHSS). Treatment involved withholding the administration of both menotrophins and human chorionic gonadotrophin for a number of days, while continuing gonadotrophin-releasing hormone agonist until the plasma oestradiol concentration fell to < 3000 pg/ml ('prolonged coasting'). The mean number of oocytes retrieved was 21.0, while the mean number of embryos transferred per procedure was 5.4. There were 21 clinical pregnancies (i.e. pregnancy rate of 41% per oocyte retrieval), 19 of which resulted in live births (i.e. a live birth rate of 37% per oocyte retrieval). Two pregnancies miscarried and there were four multiple gestations (three sets of twins and one set of triplets). None of the women developed severe OHSS. Prolonged coasting is an effective method of preventing the occurrence of severe OHSS without necessitating the cancellation of the IVF cycle or compromising success rates.

This study was undertaken to explore whether intervention with heparin and aspirin (H/A) in selected patients undergoing in-vitro fertilization (IVF) and embryo transfer could improve fecundity rates. Specifically, it explored the possibility that women diagnosed with organic pelvic disease who demonstrated antiphospholipid antibodies (APA) could benefit from H/A administration in a similar manner to that used in patients with recurrent pregnancy loss. We used an enzyme-linked immunosorbent assay for six different phospholipids to identify patients who expressed APA before they underwent IVF/embryo transfer. This study was confined to the first IVF/embryo transfer cycle that followed assessment of APA status and accordingly, the number of IVF/embryo transfer cycles corresponds with the number of patients treated. APA seropositive patients were treated with aspirin, 81 mg orally q.d., and heparin 5000 IU s.c. b.i.d., beginning on day 1 of controlled ovarian stimulation. The endpoint for success was a live birth or an ultrasound confirming fetal cardiac activity (a viable pregnancy). The prevalence of APA in patients diagnosed with organic pelvic disease (53%) was much higher than in those without female pathology (14%). The administration of H/A to APA seropositive patients significantly (P < 0.05) improved the viable pregnancy rate (49%) compared to the untreated APA seropositive group (16%). The viable pregnancy rate for APA seropositive women treated with H/A was also significantly (P < 0.001) higher than for untreated APA seronegative patients (27%). We conclude that all women undergoing IVF/embryo transfer should be tested for APA prior to initiating ovarian stimulation and those with APA seropositivity should be treated with H/A.

Ovum donation and in-vitro fertilization (IVF) surrogacy can help couples with difficult infertility problems achieve pregnancy. Most centres using oral oestrogens and oestradiol patches report pregnancy rates in the range of 30% per cycle. Parenteral oestradiol valerate has pharmacological properties that make it an attractive option for preparing the endometrium in the recipients undergoing these procedures. When the egg providers were under age 35 years, and using oestradiol valerate in the recipients, we achieved a 61% clinical pregnancy rate in 62 cycles. These improved results suggest that parenteral oestradiol valerate should be used to prepare the endometrium in recipients, and that the hormonal milieu of the endometrium plays an important role in the higher implantation rates obtainable in ovum donor and IVF surrogate cycles.

A total of 816 women who underwent 1332 cycles of ovarian stimulation for in-vitro fertilization and embryo transfer (IVF/ET) had sonographic assessments of the endometrium within 2 days of oocyte retrieval. Endometrial linings were classified on the basis of thickness and echogenicity, using a grading system described previously. Grades I and IIB ('poor') were associated with a 6% viable pregnancy rate (advanced beyond 12 weeks' gestation) compared with a 29% rate for Grade IIA ('optimal'). In a subset of 112 women with poor endometrial linings during natural cycles, eight out of 21 women (38%) under 40 years of age developed optimal linings following ovarian stimulation with menotrophins, while 19 out of 91 women (21%) aged 41-45 years converted to optimal linings. Twenty-two out of 47 women (44%) who failed to develop optimal endometrial linings following ovarian stimulation converted to Grade IIA during subsequent cycles of exogenous oestrogen replacement. The financial, emotional, and physical burden associated with IVF/ET demands that patients with poor endometrial linings following ovarian stimulation with menotrophins be counselled with regard to either cancelling their cycles of treatment, or having their embryos cryopreserved for transfer to the uterus during a subsequent hormonal replacement cycle.

Recent reports in the literature have focused on the increased risk of heterotopic pregnancy after the transfer of multiple concepti or oocytes. In an international collaborative patient registry between 1985 and 1989, 601 clinical pregnancies resulted from 2092 gamete intra-Fallopian transfer (GIFT) retrieval cycles. Five of the pregnancies were heterotopic (0.83%). After surgical intervention, all five cases of combined gestation resulted in live birth from intrauterine pregnancies. Routine vaginal ultrasonographic examination of the adnexa in patients who conceive after GIFT may help early diagnosis of heterotopic pregnancy. If the diagnosis is made early, conservative treatment may preserve the future fecundity of the patient and more intrauterine pregnancies may be salvaged.