Vitamin D Half-life in Pregnancy and Lactation

Study Overview
=================
Brief Summary
-----------------
This study measures the plasma half-life of 25-hydroxyvitamin D3 (25(OH)D3) in non-pregnant-non-lactating women, pregnant women at 30 wk gestational age and at 3 months post-partum in women who are exclusively breast-feeding.

Official Title
-----------------
Vitamin D Half-life in Pregnancy and Lactation

Conditions
-----------------
Pregnancy, Lactation

Intervention / Treatment
-----------------
* Other: Oral dose of stable isotope labeled 25(OH)D3


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: All participants: Currently resident in West Kiang and planning to stay for the next 5 months Aged between 18 and 45 y Pregnancy: > 20 wk < 30 wk pregnant (gestational age assessment by ultrasound) Singleton fetus Lactation: Breast feeding Exclusion Criteria: All participants: Severe anaemia (haemoglobin < 7 g/dL) (as per ENID protocol) Known sickle cell anaemia Known to be asthmatic or allergic to peanuts (already excluded from ENID) Known history of liver, kidney, gut or malabsorption problems Other chronic condition On prescription medication Taking vitamin D supplements (> 200 IU/d) Broken bone in last 3 y Recent infection or illness (2 weeks prior to the start of a study period) Reported onset of menopause (already excluded from ENID) Malaria parasitemia (prior to study period) Unable to consent Pregnant: Pregnancy-related complications or on discretion of mid-wife Known HIV positive Lactation: Health problem of mother or infant that may affect feeding practices

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
-----------------
Female

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Non-pregnant, non-lactating (NPNL)<br>NPNL women are age and parity matched to pregnant women. Each NPNL women is studied twice, approximately 3 months apart. At each study period the participant receives (as the intervention) a single oral dose of stable isotope labeled 25(OH)D3. | Other: Oral dose of stable isotope labeled 25(OH)D3<br>* At each measurement, women are given an oral dose of stable isotope labelled 25(OH)D3. Blood and urine samples are collected at baseline and on day 21 post-dose. Additional blood samples are collected post-dose on days 6,9,24,27 and 30.<br>|
| Experimental: Pregnant/Lactating<br>Pregnant women receive (as the intervention) a single oral dose of stable isotope labeled 25(OH)D3. The same women are followed-up in lactation to repeat the same protocol. | Other: Oral dose of stable isotope labeled 25(OH)D3<br>* At each measurement, women are given an oral dose of stable isotope labelled 25(OH)D3. Blood and urine samples are collected at baseline and on day 21 post-dose. Additional blood samples are collected post-dose on days 6,9,24,27 and 30.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma concentration of stable isotope labeled 25(OH)D3 | The plasma half-life of 25(OH)D3 is calculated from the slope (k) of the disappearance of the stable isotope labeled 25(OH)D3 against time using the equation half-life=0.693/k | Samples collected on day 6, 9, 21, 24, 27 and 30 post-dose | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plasma concentration of vitamin D metabolites and related calciotropic hormones | Analytes: 25(OH)D3, 24,25(OH)2D3, 1,25(OH)2D, vitamin D binding protein, parathyroid hormone, albumin, ionised calcium, phosphate | Fasting plasma samples collected at baseline and 21 days post-dose | 
| Urinary concentration of calcium, phosphate, creatinine and cyclic adenosine monophosphate (cAMP) | 2-hour fasting urine collection | Samples collected at baseline and 21 days post-dose | 
| Weighed dietary intake | Dietary nutrient intakes assessed by 2-day weighed food diary and nutrient intakes calculated using DINO (diet in nutrients out) analysis programme (Fitt et al, 2015) | 2 days within 30 days of dose | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
vitamin D, Africa