Here is the design of a clinical trial:

Official Title: Clinical Study of STI Screening to Prevent Adverse Birth and New-born Outcomes

Included conditions:
- Sexually Transmitted Infection
- HIV/AIDS
- Cost-effectiveness
- Birth Outcomes
- Vaginal Microbiome
- Neisseria Gonorrhoeae
- Chlamydia Trachomatis
- Trichomonas Vaginalis
- Antenatal Care
- Pregnancy

Study Armgroups:
- {'label': 'Test at 1st ANC + Test-of-Cure (Treatment 1)', 'type': 'EXPERIMENTAL', 'description': 'Single point-in-time diagnostic screening plus test-of-cure three weeks post-treatment', 'interventionNames': ['Diagnostic Test: First antenatal care + test-of-cure']}
- {'label': 'Test at 1st ANC + 30-34 gestation (Treatment 2)', 'type': 'EXPERIMENTAL', 'description': 'Repeated diagnostic screening at first antenatal care and 30-34 weeks gestation', 'interventionNames': ['Diagnostic Test: First antenatal care + week 30-34 gestation (no test-of-cure)']}
- {'label': 'Syndromic Management (Control)', 'type': 'NO_INTERVENTION', 'description': 'Syndromic management (standard of care) at every antenatal care visit per South African National Guidelines.'}

Interventions:
- {'type': 'DIAGNOSTIC_TEST', 'name': 'First antenatal care + test-of-cure', 'description': 'Single point-in-time molecular point-of-care diagnostic screening and treatment for Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis at first antenatal care visit and infection-specific test-of-cure 3 weeks post-treatment. Women with a positive test-of-cure will be re-treated. As CT/NG is a combined Xpert test, women who present with an incident infection (newly diagnosed infection) will be treated and managed accordingly.', 'armGroupLabels': ['Test at 1st ANC + Test-of-Cure (Treatment 1)']}
- {'type': 'DIAGNOSTIC_TEST', 'name': 'First antenatal care + week 30-34 gestation (no test-of-cure)', 'description': 'Repeated molecular point-of-care diagnostic screening and treatment for Chlamydia trachomatis, Neisseria gonorrhoeae and Trichomonas vaginalis at first antenatal care visit and at week 30-34 gestation. No test-of-cure will be conducted for women with positive test results; however, additional treatment will be provided to women with persistent/recurrent vaginal discharge.', 'armGroupLabels': ['Test at 1st ANC + 30-34 gestation (Treatment 2)']}

Primary Outcomes:
- {'measure': 'Frequency of adverse birth outcomes among study arms', 'description': 'Adverse birth outcomes as defined by a composite measure of preterm birth (born alive before 370/7 weeks gestation) or low birth weight (less than 2500g) as recorded in the maternity case records', 'timeFrame': 'Recorded within 2 weeks of delivery'}

Please estimate the sample size based on the assumption: 
The calculations assume a significance level that provides at least 80% power, with base rates for adverse birth outcomes ranging from 30 to 50% and pregnancy STI rates from 30 to 50%. An attrition rate of 15% is also assumed.
Sample size and power calculations
        Aim 1 analyses will explore intervention effects on reducing probabilities for adverse birth outcomes and STI prevalence at time of delivery. Based on a total sample size of 2500 participants (833â834 participants in each study arm), calculations show that we will have at least 80% power to detect study arm absolute differences of approximately 10% or larger in the frequency of adverse birth outcomes. We conducted two sets of calculations. (1) Calculations for the probability of an adverse birth event were conducted in PASS 2008 software (https://www.ncss.com/) for differences in proportions at a single time point (i.e., at birth). Calculations were run for a range of base rates ranging from 30 to 50%; this is in line with base rates from preliminary data (~â40%). (2) We calculated changes in STI prevalence based on two time points (i.e., first ANC visit and birth) and conducted simulation studies in two steps. First, we simulated STI data from a binomial distribution with parameter values based on preliminary data. Preliminary results gave pregnancy STI rates around 40%; simulations used a range of pregnancy STI rates from 30 to 50%. Based on preliminary data, we anticipate that the intervention will reduce STI rates by 20% (absolute). We assumed an attrition rate of 15%.