This is a randomised, double blind, multi-center, placebo-controlled study of subcutaneous NT100 in pregnant women with a history of unexplained recurrent pregnancy loss. Approximately 150 participants will be randomised to receive subcutaneous NT100 or placebo.

This is a randomised, double blind, multi-center, placebo-controlled study of subcutaneous NT100 in pregnant women with a history of unexplained recurrent pregnancy loss. Approximately 150 participants will be randomised to receive subcutaneous NT100 or placebo. Participants will be screened for eligibility, and will begin attempts at spontaneous conception. Following randomization and initiation of study drug treatment, participants will visit the study site at specified intervals throughout the study for assessments and blood work.

All participants will be monitored for adverse events. All participants who have received at least one dose of study drug will be followed for safety for a minimum of 4 weeks following the last dose of study drug. After delivery, pregnancy outcome information will be obtained.

Inclusion Criteria:

1. Pre-menopausal female 18-37 years of age at consent, trying to conceive
2. Documented history of unexplained recurrent pregnancy loss
3. Spontaneous conception, as confirmed by urine pregnancy test performed at the investigative site
4. Body mass index (BMI) of 19-35 kg/m2 at consent

Exclusion Criteria:

1. Greater than 5 weeks of gestation when presenting for randomisation.
2. Known karyotype abnormalities in either the participant or her current male partner
3. Uncorrected clinically significant intrauterine abnormalities
4. Abnormal vaginal bleeding of unknown cause
5. Current diagnosis of infertility in either the participant or her current male partner
6. Current or past diagnosis of systemic autoimmune disease, coagulopathy, hyperprolactinemia, cervical incompetence, or high-grade cervical dysplasia with conization/surgery.
7. Any uncontrolled clinically significant medical condition