Please select the eligibility criteria that correspond to the clinical trial below.
Title: Vitamin D Status in the First 9 Months of Life
Brief Summary: In this study the investigators wanted to assess vitamin D status and possible consequences of low plasma 25-hydroxyvitamin D levels in a population of healthy mothers and their infants, in the community of Aarhus, Denmark.


Options:
A: Inclusion criteria

* Currently lactating mothers at least 18 years of age
* Willing to continue exclusively breastfeeding their infant throughout the study interval
* The infant is 1-6 months of age at the beginning of the study
* Willing and able to participate in all aspects of the study
* Mother and infant are in good health, as determined by the study investigator
* Have been provided with, understand, and have signed the informed consent for themselves and their child.

Exclusion criteria

* Have recently travelled (within the preceding 30 days) or plan to travel south of 35 degrees north latitude during the study interval
* Have recently or plan to engage in indoor tanning
* Are currently taking medications that affect vitamin D metabolism, like steroids, anticonvulsants, or barbiturates
* Are nursing multiple infants (e.g. twins)
* Are taking greater than the daily recommended intake of 1000 mg elemental calcium as calcium supplements
* Are taking greater than the standard daily dose of 400 IU of vitamin D found in prenatal vitamins
* Infant weight below 1.67 kg
* Mothers with baseline 25(OH)D levels \>70 ng/ml, and/or infants with baseline 25(OH)D levels \>70 ng/ml
* History of kidney stones
B: Inclusion Criteria:

Each participant must meet the following criteria to be included in this study:

* Healthy, term (born no earlier than 2 weeks before estimated date of delivery), predominantly breastfeeding infants aged 6 to 12 weeks (inclusive) who are expected to be predominantly breastfed for at least 6-months. This will be determined by answering yes/no to question 'do you intend/wish to breastfeed until your infant is at least 6 months of age.' Up to one bottle (approx. 120mL) of formula per 24 hours at the time of screening is acceptable, as this will contain \<100 IU vitamin D.
* Has a parent/legally acceptable representative (LAR) capable of understanding the informed consent document and providing consent on the subject's behalf,
* The parent must expect to be able to complete 4 online questionnaires over the infant's first 12 months of life and for the infant to be available for skin prick testing (+/- food challenge) at The Royal Children's Hospital at 12 months of age.

Exclusion Criteria:

Participants meeting any of the following criteria will be excluded from the study:

* Infants who are currently receiving vitamin D supplementation
* Infants on medication that interferes with vitamin D metabolism
* Poor health due to a current or past significant disease state or congenital abnormality.
* Prematurity \<37 weeks/low birth weight \<2500 g/Small for gestational age (SGA)
* Unable to provide consent without the aid of an interpreter.
* Women at high risk of vitamin D deficiency with infants on vitamin D supplementation.
C: Inclusion Criteria:

* Women aged 18 to \<35 years.
* Current residence in Dhaka at a fixed address
* Plans to have the delivery performed at the Shimantik maternity center, and to stay in Dhaka throughout the pregnancy and for at least one month past the date of delivery.
* Gestational age of 26th to 29th (inclusive), estimated based on the first day of the last menstrual period (LMP).

Exclusion Criteria:

* Use of any dietary supplement containing more than 400 IU/day (10 mcg/day) of vitamin D within the month prior to enrolment, or refusal to stop taking supplemental vitamin D at any dose after enrollment.
* Current use of anti-convulsant or anti-mycobacterial (tuberculosis) medications.
* Severe anemia (hemoglobin concentration \< 70 g/L).
* Complicated medical or obstetric history that may increase the risk of preterm birth or labor/delivery complications, based on self-report or clinical assessment by physician (e.g., cardiovascular disease, uterine hemorrhage, placenta previa, threatened abortion, hypertension, preeclampsia, preterm labor, or multiple gestation).
* Prior history of delivery of an infant with a major congenital anomaly, birth asphyxia, or perinatal death (stillbirth or death within first week of life).
D: Inclusion Criteria:

* Healthy pregnant Caucasian women aged 24-41 years,
* A normal pregnancy giving birth between 38-42 gestational weeks.

Exclusion Criteria:

* Chronic diseases,
* Other ethnic origin than Caucasian, and
* Alcohol or drug abuse.

Answer: D