Microchimerism in Patients With Recurrent Pregnancy Losses

sRPL patient (proband): Inclusion Criteria: * ≥3 consecutive pregnancy losses ≤12 weeks of gestation, which do not include confirmed ectopic or molar pregnancies. * Age \<41 years at time of admission * Patients who have minimum one alive older brother with a common mother and prior birth of a boy, and patients who have minimum one alive older brother with a common mother and prior birth of a girl. Exclusion Criteria: * Significant intrauterine malformations * Thyroid dysfunction * Known chromosomal abnormality * An older brother, a son or a daughter from whom we cannot not collect a swab test e.g., due to lack of consent, death, distance etc. * Transplant recipient * Transfusion recipient * Pregnancy at the time the blood sample is collected Older Brother: Inclusion Criteria: * Age difference between proband and the older brother \<15 years * Common mother with the proband sRPL patient's child: Inclusion Criteria: * Age \<15 years