Serum Progesterone and Threatened Abortion During Lactation

NCT07357922 | Not Yet Recruiting

• 1 other identifier: 2025/517
• Study Type: observational
• Target: 150
• Locations: 0 countries
• Sites: N/A

Brief Summary

This study aims to evaluate the effect of first-trimester maternal serum progesterone levels on threatened abortion in women who conceive during the lactation period. Serum progesterone concentrations will be measured in lactating pregnant women during the first trimester, and their association with the etiology of threatened abortion will be analyzed. Threatened abortion is defined as vaginal bleeding occurring in the first trimester of pregnancy and represents a risk for early pregnancy loss. Previous studies have shown that serum progesterone levels may be lower in cases of threatened abortion compared to healthy pregnancies and play an essential role in predicting miscarriage risk. Serum progesterone is therefore considered a useful biomarker for assessing pregnancy viability and prognosis. During lactation, progesterone levels may vary depending on breastfeeding duration and maternal hormonal status, and generally remain low, similar to follicular-phase levels in non-pregnant women. However, normal reference values during lactation are not well established. This study aims to contribute new data to the limited literature on the relationship between lactation, serum progesterone levels, and threatened abortion, and to provide insights that may help improve early pregnancy loss prevention strategies.

Conditions

Threatened Abortion

Keywords

Serum Progesterone Levels; Threatened Abortion; Lactation During Pregnancy

Outcome Measures

Primary Outcomes (1)

• Incidence of Threatened Abortion in Lactating Pregnant Women

  The incidence of threatened abortion, defined as first-trimester vaginal bleeding with a viable intrauterine pregnancy, assessed by clinical evaluation and ultrasonographic confirmation.

  From enrollment in the first trimester until 14 weeks of gestation

Secondary Outcomes (3)

• First-Trimester Serum Progesterone Levels

  At enrollment during the first trimester of pregnancy

• Early Pregnancy Loss

  Up to 14 weeks of gestation

• Serum Progesterone Cut-off Value for Predicting Threatened Abortion

  During the first trimester of pregnancy

Study Arms (1)

Lactating Pregnant Women (First Trimester)

Pregnant women who conceived during the lactation period and are in the first trimester of pregnancy. Maternal serum progesterone levels will be measured at enrollment. Participants will be prospectively followed to evaluate the occurrence of threatened abortion, defined as first-trimester vaginal bleeding with a viable intrauterine pregnancy. This is a prospective observational cohort study, and no interventions are assigned.

Eligibility Criteria

• Age: 18 Years - 50 Years
• Gender Eligibility Details: Eligibility is limited to individuals of female biological sex who are pregnant and in the lactation period.
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

Study Population

The study population consists of lactating pregnant women aged 18 to 50 years who present for routine antenatal care during the first trimester of pregnancy at the participating obstetrics and gynecology clinics. Eligible participants include women who conceived while breastfeeding and have available first-trimester serum progesterone measurements. Participants will be prospectively followed to evaluate the occurrence of threatened abortion and early pregnancy outcomes.

You may qualify if:

• Female participants aged 18 to 50 years.
• Pregnant women who conceived during the lactation period.
• Singleton pregnancy.
• First-trimester pregnancy.
• Availability of first-trimester serum progesterone measurement obtained as part of routine antenatal care.
• Ongoing follow-up at the participating hospitals.

You may not qualify if:

• Age under 18 years or over 50 years.
• Multiple pregnancies.
• Known chronic medical diseases.
• Use of progesterone supplementation before serum progesterone measurement.
• Missing or incomplete clinical or laboratory data.

Sponsors & Collaborators

• Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization: lead

Related Publications (2)

• Sammut L, Bezzina P, Gibbs V, Muscat-Baron Y, Agius-Camenzuli A, Calleja-Agius J. Predicting first-trimester pregnancy outcome in threatened miscarriage: A comparison of a multivariate logistic regression and machine learning models. Radiography (Lond). 2025 Oct;31(6):103159. doi: 10.1016/j.radi.2025.103159. Epub 2025 Sep 4.

  PMID: 40912049 BACKGROUND

• Jiang TT, Zhang DY, Liu ZY, Lu ZS, Yan LM, Sun S, Xie JA, Zhu M, Zhang ZH, Wan YH, Wang H, Hao JH, Zhang C. Association of co-exposure to EDCs in early pregnancy with threatened abortion: The mediation effect of progesterone. Environ Int. 2026 Jan;207:110001. doi: 10.1016/j.envint.2025.110001. Epub 2025 Dec 11.

  PMID: 41391232 BACKGROUND

MeSH Terms

Conditions

Abortion, Threatened

Condition Hierarchy (Ancestors)

Pregnancy Complications; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases

Study Officials

• Burak D. Aydoğdu, M.D.

  Prof. Dr. Cemil Tascıoglu Education and Research Hospital Organization

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Burak D Aydoğdu, M.D.

CONTACT

+90 539 618 2228; burakd.1992@hotmail.com

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Target Duration: 4 Months
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: M.D.

Study Record Dates

• First Submitted: January 14, 2026
• First Posted: January 22, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): December 31, 2027
• Study Completion (Estimated): January 1, 2028
• Last Updated: January 26, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share