This prospective observational cohort study aims to compare immediate postpartum insertion (within 72 hours after delivery) versus delayed insertion (4-6 weeks postpartum) of the etonogestrel subdermal implant (Implanon-NXT®️) regarding side effects, bleeding patterns, implant-related complications, breastfeeding outcomes, continuation rates, and patient satisfaction.

The study will be conducted at Assiut General Hospital and will include 100 postpartum women aged 18-45 years who delivered at term and chose Implanon-NXT®️ as their contraceptive method. Participants will be divided into two groups according to timing of insertion: immediate postpartum and delayed postpartum insertion.

Baseline assessment will include detailed medical and obstetric history, clinical examination, complete blood count, coagulation profile, liver function tests, and breastfeeding evaluation. Implant insertion will be performed according to standard IMPLANON-NXT®️ guidelines under aseptic conditions by trained clinicians.

Participants will be followed at 6 weeks, 3 months, 6 months, and 12 months after insertion. Follow-up evaluation will include assessment of bleeding patterns using WHO Belsey definitions, implant-site complications, breastfeeding status, side effects, continuation rates, unintended pregnancy, and patient satisfaction using a validated Likert-scale questionnaire. Laboratory investigations and transvaginal Doppler ultrasound of the uterine artery will also be performed during follow-up visits.

Data will be analyzed using IBM SPSS version 29. Statistical significance will be considered at p < 0.05. The study aims to provide evidence regarding the optimal timing of postpartum Implanon-NXT®️ insertion to improve contraceptive outcomes and patient satisfaction.

2.4.1- Type of study: A prospective observational cohort study. 2.4.2- Study Setting: Assiut General Hospital . 2.4.3- Study subjects:

1. Inclusion Criteria:

   1. Women who delivered vaginally or by caesarean section at term (≥37 weeks of gestation).
   2. Age between 18 and 45 years.
   3. Desire to use the etonogestrel subdermal implant (Implanon-NXT®) as a method of contraception.
   4. Willing to provide written informed consent prior to enrollment.

2. Exclusion Criteria:

   1. Known or suspected current pregnancy.
   2. Postpartum hemorrhage requires uterotonic therapy at the time of planned insertion.
   3. Chorioamnionitis, puerperal sepsis, or any active pelvic or systemic infection at the time of insertion.
   4. Not eligible for Implanon-NXT insertion according to WHO criteria
   5. Known hypersensitivity to etonogestrel or any component of the implant device.
   6. Inability or unwillingness to provide written informed consent.

C. Sample Size Calculation:

Based on determining the main outcome variable, the estimated minimum required sample size is 90 women (45 women per group).

The sample size was calculated using G*Power software version 3.1.9.4, based on a previous randomized controlled trial, the proportion of abnormal bleeding was estimated to be 51.1% in the immediate insertion group and 23.8% in the delayed insertion group .

The main statistical test used was the Chi-square test to detect the difference between two independent proportions.

An equal classification ratio (1:1) between the two groups was assumed. A significance level (α) of 0.05 and a study power of 80% were considered.

To compensate for possible loss to follow-up, an additional 10% was added, resulting in a final sample size of 100 women (50 per group).

2.4.4 - Study tools (in detail, e.g., lab methods, instruments, steps, chemicals, …): During the screening, all eligible postpartum women will be assessed, the study explained, and written informed consent obtained from each participant.

Postpartum women aged 18-45 years who delivered at term and desire long-acting reversible contraception.

Menstrual/bleeding calendars will be used to record bleeding days as recommended by the World Health Organization (WHO) Belsey definitions of bleeding patterns with contraceptive use .

Eligible women will be recoded in and classified into two cohorts according to the timing of

• (immediate postpartum insertion, minutes 72 hours after delivery)
• (delayed postpartum insertion, at 4-6 weeks postpartum).

II. Initial evaluation (before insertion):

1. Clinical evaluation: Detailed history (age, parity, obstetric history, medical and drug history, allergies), vital signs, general and local examination.
2. Investigations: Complete blood count, coagulation profile, and liver function tests.
3. Breastfeeding assessment: initiation of breastfeeding documented before insertion.

III. Implant Insertion Procedure A. Pre-Insertion Requirements

Before inserting IMPLANON-NXT®, the trained clinician must confirm all of the following:

1. The woman is not pregnant and has no contraindication to the use of IMPLANON-NXT®.
2. A relevant medical history and physical examination, including a gynecologic examination, have been completed.
3. The woman has been counseled on the benefits, risks, and expected changes in menstrual bleeding patterns associated with the implant.
4. The woman has received and reviewed the Patient Labeling included in the packaging.
5. Written informed consent has been obtained and filed in the woman's medical record.
6. The woman has no known allergy to the antiseptic or local anesthetic agent to be used during the procedure.

B. Required Equipment

• Examination table
• Sterile surgical drapes and sterile gloves
• Antiseptic solution and surgical marker
• Local anesthetic (e.g., 1% lidocaine), needles, and syringe
• Sterile gauze, adhesive bandage, and pressure bandage
• Sterile preloaded disposable IMPLANON-NXT® applicator (inspect packaging for breaches of integrity before use)

C. Insertion Procedure Organon USA Inc. IMPLANON-NXT® (etonogestrel implant)

IV. FOLLOW UP. Follow-up visits will be for 6 weeks, 3 months, 6 months, and 12 months after insertion with the following assessments .

II. Post-insertion follow up:

Follow-up visits will be for 6 weeks, 3 months, 6 months, and 12 months after insertion with the following assessments:

A. Clinical Assessment:

1. Implant site evaluation: Check for correct position, displacement, infection, or other local complications.
2. Bleeding pattern assessment: Using WHO Belsey bleeding definitions.
3. Breastfeeding status: Exclusive, partial, or cessation of breastfeeding, and time to cessation.
4. Side effects: Headache, mood changes, weight change, acne.
5. Patient satisfaction: Assessed using a validated Likert-scale questionnaire.
6. Unintended pregnancy: Confirmed by urine or blood pregnancy test at each visit if clinically indicated.
7. Contraceptive continuation: Document whether the implant remains in situ or has been removed (and reason for removal).

B. Laboratory investigations:

Blood pressure, Body weight / BMI, Urine pregnancy test and complete blood count at 3 months and 6 months post-insertion to monitor for anemia.

C. Transvaginal Ultrasound Doppler of the Uterine Artery

Evaluated at each visit (6 weeks, 3 months, 6 months, and 12 months):

1. Size of uterus - three dimensions measured (length × anteroposterior × transverse diameter in cm) as an indirect marker of uterine involution
2. Endometrial thickness - measured in the sagittal plane at the thickest point (mm)
3. Uterine artery Pulsatility Index (PI) measured bilaterally; mean UtA-PI calculated
4. Ovaries Ovarian size, Ovarian volume, Follicular activity, Ovarian cysts, Evidence of ovarian suppression and any adnexal pathology .

Inclusion Criteria:

1. Women who delivered vaginally or by caesarean section at term (≥37 weeks of gestation).
2. Age between 18 and 45 years.
3. Desire to use the etonogestrel subdermal implant (Implanon-NXT®) as a method of contraception.
4. Willing to provide written informed consent prior to enrollment.

Exclusion Criteria:

• 1. Known or suspected current pregnancy. 2. Postpartum hemorrhage requires uterotonic therapy at the time of planned insertion.

  3. Chorioamnionitis, puerperal sepsis, or any active pelvic or systemic infection at the time of insertion.

  4. Not eligible for Implanon-NXT insertion according to WHO criteria 5. Known hypersensitivity to etonogestrel or any component of the implant device.

  6. Inability or unwillingness to provide written informed consent. (2)

Postpartum women aged 18-45 years who delivered at term and desire long-acting reversible contraception.

No individual participant data (IPD) will be shared. Due to confidentiality and ethical restrictions in accordance with the Faculty of Medicine, Assiut University policy, sharing de-identified raw data with other researchers or organizations is not planned.

This update was made to comply with the registry's mandatory requirement for an IPD sharing statement. The revised response clarifies our intention regarding the sharing of de-identified individual participant data, which will not be shared due to confidentiality and ethical considerations.