BACKGROUND: The reproductive impact of adenomyosis and endometriosis is widely researched but the extent of these impacts remains elusive. It has been demonstrated that endometriosis, in particular, is known to result in subfertility but endometriosis and adenomyosis are increasingly linked to late pregnancy complications such as those caused by placental insufficiency. At the molecular level, the presence of ectopic endometrium perturbs the endometrial hormonal, cellular, and immunological milieu, negatively influencing decidualization, placentation, and developmental programming of the embryo. It is unclear if and how such early aberrant reproductive development relates to pregnancy outcomes in endometriosis and adenomyosis. OBJECTIVE AND RATIONALE: The aims of this systematic review and meta-analysis were to (i) investigate the association of adenomyosis and endometriosis with fertility, obstetric, and neonatal outcomes of women through both assisted reproduction and natural conception and (ii) determine whether endometriosis disease subtypes have specific impacts on different stages of the reproductive process. SEARCH METHODS: A systematic literature review of NHS evidence electronic databases and the Cochrane database identified all comparative and observational studies between 1980 and December 2018 in any language on adenomyosis and endometriosis with fertility, obstetric, and neonatal outcomes (23 search terms used). A total of 104 papers were selected for data extraction and meta-analysis, with use of Downs and Black standardized checklist to evaluate quality and bias. OUTCOMES: We found that endometriosis consistently leads to reduced oocyte yield and a reduced fertilization rate (FR), in line with current evidence. Milder forms of endometriosis were most likely to affect the fertilization (FR OR 0.77, CI 0.63–0.93) and earlier implantation processes (implantation rate OR 0.76, CI 0.62–0.93). The more severe disease by American Society for Reproductive Medicine staging (ASRM III and IV) influenced all stages of reproduction. Ovarian endometriosis negatively affects the oocyte yield (MD −1.22, CI −1.96, −0.49) and number of mature oocytes (MD −2.24, CI −3.4, −1.09). We found an increased risk of miscarriage in both adenomyosis and endometriosis (OR 3.40, CI 1.41–8.65 and OR 1.30, CI 1.25–1.35, respectively), and endometriosis can be associated with a range of obstetric and fetal complications including preterm delivery (OR 1.38, CI 1.01–1.89), caesarean section delivery (OR 1.98 CI 1.64–2.38), and neonatal unit admission following delivery (OR 1.29, CI 1.07–1.55). WIDER IMPLICATIONS: Adenomyosis and the subtypes of endometriosis may have specific complication profiles though further evidence is needed to be able to draw conclusions. Several known pregnancy complications are likely to be associated with these conditions. The complications are possibly caused by dysfunctional uterine changes leading to implantation and placentation issues and therefore could potentially have far-reaching consequences as suggested by Barker’s hypothesis. Our findings would suggest that women with these conditions should ideally receive pre-natal counselling and should be considered higher risk in pregnancy and at delivery, until evidence to the contrary is available. In order to expand our knowledge of these conditions and better advise on future management of these patients in reproductive and maternal medicine, a more unified approach to studying fertility and reproductive outcomes with longer term follow-up of the offspring and attention to the subtype of disease is necessary.

Endometriosis is a disease known to be detrimental to fertility. Women with endometriosis, and the presence of endometrioma, may require artificial reproductive techniques (ART) to achieve a pregnancy. The specific impact of endometrioma alone and the impact of surgical intervention for endometrioma on the reproductive outcome of women undergoing IVF/ICSI are areas that require further clarification. The objectives of this review were as follows: (i) to determine the impact of endometrioma on IVF/ICSI outcomes, (ii) to determine the impact of surgery for endometrioma on IVF/ICSI outcome and (iii) to determine the effect of different surgical techniques on IVF/ICSI outcomes. We performed a systematic review and meta-analysis examining subfertile women who have endometrioma and are undergoing IVF/ICSI, and who have or have not had any surgical management for endometrioma before IVF/ICSI. The primary outcome was live birth rate (LBR). Our secondary outcomes were clinical pregnancy rate (CPR), mean number of oocyte retrieved (MNOR), miscarriage rate (MR), fertilization rate, implantation rate, antral follicle count (AFC), total stimulating hormone dose, and any rates of adverse effects such as cancellation and associated complications during the IVF/ICSI treatment. We included 33 studies for the meta-analysis. The majority of the studies were retrospective (30/33), and three were RCTs. Compared with women with no endometrioma undergoing IVF/ICSI, women with endometrioma had a similar LBR (odds ratio [OR] 0.98; 95% CI [0.71, 1.36], 5 studies, 928 women, I² = 0%) and a similar CPR (OR 1.17; 95% CI [0.87, 1.58], 5 studies, 928 women, I² = 0%), a lower mean number of oocytes retrieved (SMD −0.23; 95% CI [−0.37, −0.10], 5 studies, 941 cycles, I² = 37%) and a higher cycle cancellation rate compared with those without the disease (OR 2.83; 95% CI [1.32, 6.06], 3 studies, 491 women, I² = 0%). Compared with women with no surgical treatment, women who had their endometrioma surgically treated before IVF/ICSI had a similar LBR (OR 0.90; 95% CI [0.63, 1.28], 5 studies, 655 women, I² = 32%), a similar CPR (OR 0.97; 95% CI [0.78, 1.20], 11 studies, 1512 women, I² = 0%) and a similar mean number of oocytes retrieved (SMD −0.17; 95% CI [−0.38, 0.05], 9 studies, 810 cycles, I² = 63%). Women with endometrioma undergoing IVF/ICSI had similar reproductive outcomes compared with those without the disease, although their cycle cancellation rate was significantly higher. Surgical treatment of endometrioma did not alter the outcome of IVF/ICSI treatment compared with those who did not receive surgical intervention. Considering that the reduced ovarian reserve may be attributed to the presence of endometrioma per se, and the potential detrimental impact from surgical intervention, individualization of care for women with endometrioma prior to IVF/ICSI may help optimize their IVF/ICSI results.

Despite advances in ART, implantation and pregnancy rates per embryo transfer still remain low. IVF laboratories strive to ensure that the process of handling gametes in vitro closely mimics the in vivo environment. However, there remains a lack of knowledge regarding the in vivo regulation and dynamic variation in biophysical parameters such as oxygen concentration, pH and temperature within the reproductive tract. To undertake a systematic review of the current understanding of the physico-chemical parameters of oxygen tension (pO₂), pH and temperature within the female reproductive tract, and their potential implications in clinical and pathological processes related to fertility and those pertaining to limited reproductive capacity. A comprehensive literature search was performed using electronic databases including Medline, Embase, Cochrane Library and Pubmed to identify original and review articles addressing the biophysical parameters (pO₂, pH and temperature) in the female reproductive tract of any species. The search included all studies published between 1946 and November 2015. Search terms included ‘oxygen’, ‘pH’, ‘hydrogen ion concentration’, ‘acid base’ and others terms. We also used special features and truncations to identify synonyms and broaden the search. Studies were excluded if they only assessed embryo culture conditions, fetal acid–base status, oxidative stress, outcomes of pregnancy and measurements of these parameters in non-reproductive organs. Our search generated 18 685 records and 60 articles were included. pO₂ within the female reproductive tract shows cyclical variation and minute-to-minute oscillations, which may be influenced by uterine contractility, hormones, the autonomic system, cardiac pulsatility, and myometrial and smooth muscle integrity. Fine balanced control of pO₂ and avoidance of overwhelming oxidative stress is crucial for embryogenesis and implantation. The pH in the female reproductive tract is graduated, with lowest pH in the vagina (~pH 4.42) increasing toward the Fallopian tubes (FTs) (~pH 7.94), reflecting variation in the site-specific microbiome and acid–base buffering at the tissue/cellular level. The temperature variation in humans is cyclical by day and month. In humans, it is biphasic, increasing in the luteal phase; with the caudal region of the oviduct 1–2 degrees cooler than the cranial portion. Temperature variation is influenced by hormones, density of pelvic/uterine vascular beds and effectiveness of heat exchange locally, crucial for sperm motility and embryo development. We have identified significant deficiencies and inconsistencies in the methods used to assess these biophysical factors within the reproductive tract. We have suggested that the technological solutions including the development of methods and models for real time, in vivo recordings of biophysical parameters. The notion of ‘back to nature’ in assisted conception suggested 20 years ago has yet to be translated into clinical practice. While the findings from this systematic review do not provide evidence to change current in vitro protocols, it highlights our current inability to assess the in vivo reproductive tract environment in real time. Data made available through future development of sensing technology in utero may help to provide new insights into how best to optimize the in vitro embryo environment and allow for more precise and personalized fertility treatment.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a genetic condition affecting the structure and function of sperm flagellum and motile cilia including those in the male and female reproductive tracts. Infertility is a commonly reported feature of PCD, but there is uncertainty as to how best to counsel patients on their fertility prognosis.OBJECTIVE AND RATIONALE: This review aimed to summarize the prevalence of subfertility, possible underlying mechanisms, and the success of ART in men and women with PCD. The efficacy of ART in this patient group is relatively unknown and, hence, the management of infertility in PCD patients remains a challenge. There are no previous published or registered systematic reviews of fertility outcomes in PCD.SEARCH METHODS: Systematic literature searches were performed in Medline, Embase, Cochrane Library, and PubMed electronic databases to identify publications between 1964 and 2022 reporting fertility outcomes in men and women with PCD. Publications were excluded if they reported only animal studies, where gender was not specified or where subjects had a medical co-morbidity also known to impact fertility. Quality of evidence was assessed by critical appraisal and application of an appraisal tool for cross-sectional studies. The primary outcomes were natural conception in men and women with PCD, and conception following ART in men and women with PCD.OUTCOMES: A total of 1565 publications were identified, and 108 publications were included after screening by two independent researchers. The quality of available evidence was low. The exact prevalence of subfertility in PCD is unclear but appears to be higher in men (up to 83% affected) compared to women (up to 61% affected). Variation in the prevalence of subfertility was observed between geographic populations which may be explained by differences in underlying genotype and cilia function. Limited evidence suggests subfertility in affected individuals is likely caused by abnormal cilia motion in the fallopian tubes, endometrium and efferent ductules, and dysmotile sperm. Some men and women with PCD benefited from ART, which suggests its use should be considered in the management of subfertility in this patient group. Further epidemiological and controlled studies are needed to determine the predictors of fertility and optimal management in this patient group.WIDER IMPLICATIONS: It is important that patients with PCD receive evidence-based counselling about the potential impact of their condition on their fertility prognosis and what management options may be available to them if affected. Understanding the pathophysiology and optimal management of subfertility in PCD will increase our understanding of the role of cilia and the impact of wider secondary ciliopathies on reproduction.

It is known that lifestyle factors affect sporadic miscarriage, but the extent of this on RPL (recurrent pregnancy loss) is less well known. A systematic review and meta-analysis was performed to assess the associations between lifestyle factors and RPL. Studies that analysed RPL in the context of BMI, smoking, alcohol and caffeine intake were included. The primary and secondary outcomes were odds of having RPL in the general population and odds of further miscarriage, respectively. Underweight and women with BMI > 25 are at higher odds of RPL in the general population (OR 1.2, 95% CI 1.12–1.28 and OR 1.21, 95% CI 1.06–1.38, respectively). In women with RPL, having BMI > 30 and BMI > 25 has increased odds of further miscarriages (OR 1.77, 95% CI 1.25–2.50 and OR 1.35, 95% CI 1.07–1.72, respectively). The quality of the evidence for our findings was low or very low. Being underweight and BMI > 25 contributes significantly to increased risk of RPL (general population). BMI > 25 or BMI > 30 increases the risk of further miscarriages (RPL population). Larger studies addressing the effects of alcohol, cigarette smoking and caffeine on the risk of RPL with optimisation of BMI in this cohort of women are now needed.