Pregnancy loss is a significant life event for many couples, and accounts for a large number of presentations to an emergency department, with considerable resources being allocated to these devastated couples. While a single miscarriage may be an isolated event, most likely due to a genetic abnormality, recurrent pregnancy loss (RPL) is a separate entity. One of the most difficult aspects of dealing with these couples is the lack of consensus on whom to test, what tests to offer, and how to treat. This dilemma is compounded by the fact that every country has a different approach, with RANZCOG guidelines following the RCOG Green-top Guidelines dated 2011.¹ Europe follows the ESHRE guidelines,² dated 2018, and the USA follows the ASRM guidelines,³ dated 2012.

Background

Pregnancy loss is divided into embryonic or fetal. Embryonic is defined as a loss at ten weeks post the last menstrual period or less. Fetal losses are losses after ten weeks and up to 24 weeks. A recurrent pregnancy loss/miscarriage clinic has been held at the Women’s and Children’s Hospital (WCH) in Adelaide since 2007. Approximately 2000 patients have attended, referred from a number of different areas. Over the years, investigations have been added or discarded, depending on the available evidence. This article will discuss risk factors for recurrent miscarriage, upon which the investigations currently offered at the WCH are based, and the proposed way forward, based on the latest evidence from recurrent miscarriage groups internationally.

We offer a workup to couples with pregnancy losses after two embryonic losses, one ultrasonically confirmed fetal loss, or one embryonic and one fetal loss. We do include non-visualised losses if the histopathology was positive for pregnancy, as Kolte et al⁴ demonstrated that these losses decreased the relative risk for a live birth by 10%, which is the same impact conferred by a clinical miscarriage.

Risk factors

Epidemiological factors have been identified as risk factors for further miscarriages, including maternal and paternal age, and the number of previous miscarriages. After three consecutive pregnancy losses, the risk of a further miscarriage is estimated to be approximately 40%, and this risk increases with maternal age.¹ Environmental risk factors, such as smoking and alcohol consumption, have been linked with sporadic miscarriages, and the recent ESHRE guidelines have made the suggestion that smoking and alcohol cessation should be recommended.²

Antiphospholipid syndrome is an important, treatable cause of recurrent miscarriages with antiphospholipid antibodies present in 5–20% of women with recurrent miscarriages.^{2 5}

Chromosomal abnormalities of the embryo account for a significant proportion of miscarriages (between 30–57%) with an increase seen with advancing maternal age.¹ Parents who are carriers of a balanced translocation are at increased risk of miscarriage and these are found in 3–5% of recurrent miscarriage couples;⁶ therefore parental karyotyping is recommended by ASRM,³  but not by ESHRE,² who suggest only testing if there is an increased risk after individual assessment.

Anatomical factors, mostly uterine malformations, have been linked with recurrent miscarriage; however, the exact role they play is unclear. Both congenital and acquired uterine defects are seen in women who experience recurrent miscarriages and therefore imaging to look for septate, bicornuate, didelphys and arcuate defects, as well as fibroids and polyps, is recommended.⁶

Endocrine factors play a role in recurrent miscarriage. Overt hypothyroidism clearly increases the risk of miscarriage; however, the impact of subclinical hypothyroidism is less clear. The role that positive thyroid antibodies have is also unclear, although positive thyroid antibodies with subclinical hypothyroidism may increase miscarriage risk.⁵ Insulin resistance or hyperinsulinism has been thought to be associated with pregnancy loss, particularly in patients with polycystic ovarian syndrome.¹

The male partner is investiaged as it is believed that sperm DNA damage may contribute to adverse pregnancy outcomes, and when sperm from couples experiencing recurrent pregnancy loss was compared with sperm from couples without pregnancy loss, a lower percentage of normal sperm morphology, concentration and progressive motility was found in the pregnancy loss group compared to those without loss. Obviously, sperm quality may affect embryonic development by genetic, as well as epigenetic, mechanisms.^{7 8} These sperm-borne epigenetic marks are, in turn, affected by a variety of paternal factors, including genotype, age, obesity, smoking and exposure to environmental contaminants.⁹

Investigations

When patients are seen at the WCH recurrent pregnancy loss clinic, a thorough history is obtained from both partners, including medical history, medications, allergies, lifestyle factors and family history. The body mass index (BMI) of the patient is recorded.

We offer the following investigations to couples seen in the recurrent pregnancy loss clinic.

Females:

• Thyroid function tests (‘subclinical hypothyroidism’ is treated if the TSH is greater than 2.5 mIU/L)
• Thyroid antibodies (noted but not independently treated)
• Antiphospholipid antibodies (2 positive tests required, minimum 6 weeks apart, for positive diagnosis)
• Anti-nuclear antibodies (for information regarding other autoimmunity)
• 75g oral glucose tolerance test with insulin studies
• Fasting homocysteine levels
• Folate and B12 levels and vitamin D levels
• +/- Karyotype, if genetics of last loss unknown
• 3D pelvic ultrasound in the luteal phase of the cycle

Males:

• +/- Karyotype
• Glucose and insulin
• Homocysteine
• Folate and B12 levels and vitamin D levels

Discussion: the way forward

Khalife et al⁶ and Popescu et al¹⁰ have suggested strategies for the optimal evaluation of pregnancy losses, which include the incorporation of a 24-chromosome microarray on the products of conception (POC), as microarrays increase the chance of identifying an aneuploidy compared to conventional karyotyping, and potentially avoid maternal cell contamination. They suggest that the products from the second pregnancy loss should be tested, and if abnormal, then the expensive evaluation could be avoided in these patients. Using this method, Khalife et al detected aneuploidy in 63% of those tested, thus negating the need for the costly evaluation that could result in unnecessary treatment for presumed causes.⁶ These arrays also identified an unbalanced translocation in 4% of the POC which could have originated in the parents, hence parental karyotyping was then offered. The remaining 33% of ‘normal’ chromosome microarray analyses (CMAs) were offered a full recurrent pregnancy loss work up, as there was no other explanation for the losses. There is, however, a considerable cost involved in performing CMAs, and they may not be available in all centres.

A trial is currently underway in our centre, comparing the evaluation of the products of conception via the conventional Karyotype method or via microarrays.

Conclusion

While recurrent miscarriages are common, and regarded as minor medical issues by many emergency departments, there is increasing evidence that these patients may be a high-risk population for adverse obstetrical outcomes when they do finally become pregnant, necessitating increased antenatal surveillance. Rasmark Roepke et al, in a retrospective cohort study, showed that women suffering recurrent pregnancy loss when compared to women who had not had losses, had an increased risk of pre-eclampsia, preterm birth, small for gestational age babies, abruption and stillbirth less than 37 weeks, suggesting that these issues are associated with placental dysfunction.¹¹

Research has also shown that women who suffer recurrent miscarriages are at an increased risk of future cardiovascular disease of total coronary heart disease after adjusting for traditional cardiovascular risk factors.¹² The risk appears to be independent of BMI, hypertension, waist-to-hip ratio and white cell count.¹³

Thus, miscarriages may reflect a bigger picture of overall cardiovascular health, and as such, could be a primary healthcare issue with possible preventative interventions for this group.

1. Royal College of Obstetricians and Gynaecologists. The investigation and treatment of couples with recurrent first-trimester and second-trimester miscarriage. London: RCOG; 2011.
2. Atik RB, Christiansen OB, Elson J, et al. ESHRE guideline: recurrent pregnancy loss. Human Reproduction Open. 2018(2):hoy004.
3. Practice Committee of the American Society for Reproductive Medicine. Evaluation and treatment of recurrent pregnancy loss: a committee opinion. Fertil Steril. 2012;98(5):1103-11.
4. Kolte A, Van Oppenraaij R, Quenby S, et al. Non-visualized pregnancy losses are prognostically important for unexplained recurrent miscarriage. Human Reproduction. 2014;29(5):931-7.
5. Homer HA. Modern management of recurrent miscarriage. ANZJOG. 2019;59(1):36-44.
6. Khalife D, Ghazeeri G, Kutteh W. Review of current guidelines for recurrent pregnancy loss: new strategies for optimal evaluation of women who may be superfertile. Seminars in Perinatology. 2019;43(2):105-15.
7. Zidi-Jrah IMD, Hajlaoui AMS, Mougou-Zerelli SMDPD, et al. Relationship between sperm aneuploidy, sperm DNA integrity, chromatin packaging, traditional semen parameters, and recurrent pregnancy loss. Fertil Steril. 2016;105(1):58-64.
8. Aitken RJ, Gibb Z, Baker MA, et al. Causes and consequences of oxidative stress in spermatozoa. Reproduction, Fertility and Development. 2016;28(2):1-10.
9. Carlini T, Paoli D, Pelloni M, et al. Sperm DNA fragmentation in Italian couples with recurrent pregnancy loss. Reproductive Biomedicine Online. 2016;34(1):58-65.
10. Popescu F, Jaslow CR, Kutteh WH. Recurrent Pregnancy Loss Evaluation Combined With 24-Chromosome Microarray of Miscarriage Tissue Provides a Probable or Definite Cause of Pregnancy Loss in Over 90% of Patients. Obstetrical & Gynecological Survey. 2018;73(7):408-9.
11. Rasmark Roepke E, Christiansen OB, Källén K, Hansson SR. Women with a History of Recurrent Pregnancy Loss Are a High-Risk Population for Adverse Obstetrical Outcome: A Retrospective Cohort Study. Journal of Clinical Medicine. 2021;10(2).
12. Oliver-Williams CT, Heydon EE, Smith GCS, Wood AM. Miscarriage and future maternal cardiovascular disease: a systematic review and meta-analysis. Heart (British Cardiac Society). 2013;99(22):1636-44.
13. Parker DRS, Lu BD, Sands-Lincoln MP, et al. Risk of Cardiovascular Disease Among Postmenopausal Women with Prior Pregnancy Loss: The Women’s Health Initiative. Annals of Family Medicine. 2014;12(4):302-9.