Peer-reviewedCC BY-NC-NDF&S reports5 Aug 2026

The hidden risk: inadvertent pregnancies in random start ovarian stimulation protocols and ovarian hyperstimulation syndrome.

Ayse Seyhan^1,2
Bulent Urman¹
Baris Ata³

¹American Hospital, Department of Obstetrics and Gynecology, Centre for Reproductive Endocrinology and Infertility, Istanbul, Turkey.
²Department of Obstetrics and Gynecology, Atlas University, Istanbul, Turkey.
³Koc University, Department of Obstetrics and Gynecology, Reproductive Endocrinology and Infertility Centre, Istanbul, Turkey.

Abstract

Objective

To examine the risk of severe ovarian hyperstimulation syndrome (OHSS) when random-start ovarian stimulation (RSOS) is performed during an undetected, spontaneously conceived pregnancy.Design

A case-report.Subjects

A 24-year-old woman with polycystic ovary syndrome, a history of two early pregnancy losses, and 25 months of infertility, who underwent in vitro fertilization (IVF) with RSOS at an external fertility clinic.Exposure

The RSOS begun while an early intrauterine pregnancy was already present but unrecognized.Main outcome measures

Onset and severity of OHSS, assessed by clinical symptoms, serum human chorionic gonadotropin levels, and the need for hospitalization or intervention.Results

Following oocyte retrieval, the patient suffered severe abdominal pain and significant ascites consistent with OHSS and was found to have a concurrent intrauterine pregnancy. Outpatient management failed to control her symptoms, and she required hospitalization and termination of the pregnancy. She conceived naturally six months later and delivered a healthy infant.Conclusion

This case underscores the significant risk of undetected pregnancies during RSOS, which can lead to severe OHSS. It emphasizes the critical need for vigilant monitoring of progesterone and human chorionic gonadotropin levels and the implementation of strategies to detect potential pregnancies before trigger of oocyte maturation. Clinicians must weigh carefully the benefits of flexible stimulation protocols against the risks of unintended pregnancies, especially in patients with a reasonable chance of achieving spontaneous conception.

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Cite

BibTeX RIS

BibTeX

@article{seyhan2026hidden,
  title = {{The hidden risk: inadvertent pregnancies in random start ovarian stimulation protocols and ovarian hyperstimulation syndrome.}},
  author = {Ayse Seyhan and Bulent Urman and Baris Ata},
  journal = {F\&S reports},
  year = {2026},
  month = aug,
  doi = {10.1016/j.xfre.2026.07.006},
  url = {https://europepmc.org/article/MED/42903350},
  note = {CC BY-NC-ND},
}

RIS

TY  - JOUR
TI  - The hidden risk: inadvertent pregnancies in random start ovarian stimulation protocols and ovarian hyperstimulation syndrome.
AU  - Ayse Seyhan
AU  - Bulent Urman
AU  - Baris Ata
PY  - 2026
DA  - 2026/08/05
JO  - F&S reports
DO  - 10.1016/j.xfre.2026.07.006
UR  - https://europepmc.org/article/MED/42903350
AB  - Objective  To examine the risk of severe ovarian hyperstimulation syndrome (OHSS) when random-start ovarian stimulation (RSOS) is performed during an undetected, spontaneously conceived pregnancy.Design  A case-report.Subjects  A 24-year-old woman with polycystic ovary syndrome, a history of two early pregnancy losses, and 25 months of infertility, who underwent in vitro fertilization (IVF) with RSOS at an external fertility clinic.Exposure  The RSOS begun while an early intrauterine pregnancy was already present but unrecognized.Main outcome measures  Onset and severity of OHSS, assessed by clinical symptoms, serum human chorionic gonadotropin levels, and the need for hospitalization or intervention.Results  Following oocyte retrieval, the patient suffered severe abdominal pain and significant ascites consistent with OHSS and was found to have a concurrent intrauterine pregnancy. Outpatient management failed to control her symptoms, and she required hospitalization and termination of the pregnancy. She conceived naturally six months later and delivered a healthy infant.Conclusion  This case underscores the significant risk of undetected pregnancies during RSOS, which can lead to severe OHSS. It emphasizes the critical need for vigilant monitoring of progesterone and human chorionic gonadotropin levels and the implementation of strategies to detect potential pregnancies before trigger of oocyte maturation. Clinicians must weigh carefully the benefits of flexible stimulation protocols against the risks of unintended pregnancies, especially in patients with a reasonable chance of achieving spontaneous conception.
SN  - 2666-3341
ER  -

Abstract

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