Variable
Study site	Arkansas, California, Iowa, Massachusetts, New Jersey, New York, Texas, Georgia, North Carolina, Utah
Maternal residency ever moved B1-P2	Yes, no
Season of date of conception	Winter, spring, summer, fall
Maternal race/ethnicity	Non-Hispanic white, Hispanic foreign born, Hispanic US born, non-Hispanic black, other
Paternal race/ethnicity	Non-Hispanic white, Hispanic foreign born, Hispanic US born, non-Hispanic black, other
Maternal education	Less than high school, high school, greater than high school
Paternal education	Less than high school, high school, greater than high school
Maternal feelings about pregnancy	Wanted to be pregnant, wanted to wait until later, did not want to become pregnant, did not care, pregnant despite consistent contraceptive use
Timing of pregnancy discovery	Trimester 1, Trimester 2, or Trimester 3
Timing of first prenatal visit	Trimester 1, Trimester 2, Trimester 3, none
Household income	<$10,000, $10,000–50,000, >$50,000
Interpregnancy interval	No previous pregnancies, ≤12 months, >12 months
Obesity	Yes, no
Antihypertensive medication use during B1-P3	Yes, no
Anti-depressant medication use during B1	Yes, no
Anti-depressant medication use during P1	Yes, no
Anti-depressant medication use during P2	Yes, no
Anti-fever medication use during B1	Yes, no
Anti-fever medication use during P1	Yes, no
Anti-fever medication use during P2	Yes, no
Anti-folate medication use during B1	Yes, no
Anti-folate medication use during P1	Yes, no
Anti-folate medication use during P2	Yes, no
Anti-infective medication use during B1	Yes, no
Anti-infective medication use during P1	Yes, no
Anti-infective medication use during P2	Yes, no
Anti-psychotic medication use during B1	Yes, no
Anti-psychotic medication use during P1	Yes, no
Anti-psychotic medication use during P2	Yes, no
Anti-anxiety medication use during B1	Yes, no
Anti-anxiety medication use during P1	Yes, no
Anti-anxiety medication use during P2	Yes, no
Thyroid medication use during B1	Yes, no
Thyroid medication use during P1	Yes, no
Thyroid medication use during P2	Yes, no
Aspirin use during B1	Yes, no
Aspirin use during P1	Yes, no
Aspirin use during P2	Yes, no
NSAIDs use during B1	Yes, no
NSAIDs use during P1	Yes, no
NSAIDs use during P2	Yes, no
Opioid use during B1	Yes, no
Opioid use during P1	Yes, no
Opioid use during P2	Yes, no
Steroid use during B1	Yes, no
Steroid use during P1	Yes, no
Steroid use during P2	Yes, no
Vasoactive medication use during B1-P3	Yes, no
Antitussive use during B1	Yes, no
Antitussive use during P1	Yes, no
Antitussive use during P2	Yes, no
Epilepsy	Yes, no
Seizures	Yes, no
Respiratory disease during B1	Yes, no
Respiratory disease during P1	Yes, no
Respiratory disease during P2	Yes, no
Urinary tract infection during B1	Yes, no
Urinary tract infection during P1	Yes, no
Urinary tract infection during P2	Yes, no
Pelvic inflammatory disease during B1	Yes, no
Pelvic inflammatory disease during P1	Yes, no
Pelvic inflammatory disease during P2	Yes, no
Any type of fever during B1	Yes, no
Any type of fever during P1	Yes, no
Any type of fever during P2	Yes, no
Sexually transmitted infections during B1	Yes, no
Sexually transmitted infections during P1	Yes, no
Sexually transmitted infections during P2	Yes, no
Autoimmune disease	Yes, no
Any thyroid disease	Yes, no
Injury during B1	Yes, no
Injury during P1	Yes, no
Injury during P2	Yes, no
CT/CAT scan during B1	Yes, no
CT/CAT scan during P1	Yes, no
CT/CAT scan during P2	Yes, no
MRI during B1	Yes, no
MRI during P1	Yes, no
MRI during P2	Yes, no
Other X-ray or scan during B1	Yes, no
Other X-ray or scan during P1	Yes, no
Other X-ray or scan during P2	Yes, no
X-ray during B1	Yes, no
X-ray during P1	Yes, no
X-ray during P2	Yes, no
Surgery during B1	Yes, no
Surgery during P1	Yes, no
Surgery during P2	Yes, no
Birth control pill use during B1	Yes, no
Birth control pill use during P1	Yes, no
Birth control pill use during P2	Yes, no
Other birth control use during B1	Yes, no
Other birth control use during P1	Yes, no
Other birth control use during P2	Yes, no
Fertility treatment	Yes, no
Nausea during P1	Yes, no
Nausea during P2	Yes, no
Medication for pregnancy nausea	Yes, no
Chorionic villus sampling	Yes, no
Folic acid-containing supplement use during B1	Yes, no
Folic acid-containing supplement use during P1	Yes, no
Folic acid-containing supplement use during P2	Yes, no
Cereal intake during B1	Yes, no
Cereal intake during P1	Yes, no
Cereal intake during P2	Yes, no
Food supplement intake during B1	Yes, no
Food supplement intake during P1	Yes, no
Food supplement intake during P2	Yes, no
Cigarette smoking during B1	Yes, no
Cigarette smoking during P1	Yes, no
Cigarette smoking during P2	Yes, no
Household smoke exposure during B1	Yes, no
Household smoke exposure during P1	Yes, no
Household smoke exposure during P2	Yes, no
Work/school smoke exposure during B1	Yes, no
Work/school smoke exposure during P1	Yes, no
Work/school smoke exposure during P2	Yes, no
Alcohol consumption during B1	Yes, no
Alcohol consumption during P1	Yes, no
Alcohol consumption during P2	Yes, no
Beer intake	Yes, no
Wine intake	Yes, no
Mixed drink intake	Yes, no
Shots of liquor intake	Yes, no
Other drink intake	Yes, no
Paternal substance abuse during B1	Yes, no
Paternal substance abuse during P1	Yes, no
Paternal substance abuse during P2	Yes, no
Maternal substance abuse during B1	Yes, no
Maternal substance abuse during P1	Yes, no
Maternal substance abuse during P2	Yes, no
Frequency of showers at home	<1 per day, 1 per day, <1 per day
Frequency of baths at home	Never or <1 per month, ≥1 per month
Hot tub/jacuzzi/sauna use during B1	Yes, no
Hot tub/jacuzzi/sauna use during P1	Yes, no
Hot tub/jacuzzi/sauna use during P2	Yes, no
Maternal active military duty	Yes, no
Paternal active military duty	Yes, no
Any household participation in occupational pesticide application	Yes, no
Father employed	Yes, no
Private well drinking water source	Yes, no
Skim/low fat milk (8 oz. glass)	Never or <1 per month, ≥1 per month
Whole milk (8 oz. glass)	Never or <1 per month, ≥1 per month
Yogurt (1 cup)	Never or <1 per month, ≥1 per month
Ice cream (1/2 cup)	Never or <1 per month, ≥1 per month
Cottage or ricotta cheese (1/2 cup)	Never or <1 per month, ≥1 per month
Other cheese (1 slice or 1 oz. serving)	Never or <1 per month, ≥1 per month
Margarine (pat)	Never or <1 per month, ≥1 per month
Butter (pat)	Never or <1 per month, ≥1 per month
Apples or pears (1)	Never or <1 per month, ≥1 per month
Oranges (1)	Never or <1 per month, ≥1 per month
Orange juice (1 glass)	Never or <1 per month, ≥1 per month
Peaches, apricots, plums, or nectarines (1 fresh or 1/2 cup canned)	Never or <1 per month, ≥1 per month
Bananas (1)	Never or <1 per month, ≥1 per month
Other fruits, fresh, frozen, or canned (1/2 cup)	Never or <1 per month, ≥1 per month
Tomatoes (1) or tomato juice (small glass)	Never or <1 per month, ≥1 per month
String beans (1/2 cup)	Never or <1 per month, ≥1 per month
Broccoli (1/2 cup)	Never or <1 per month, ≥1 per month
Cabbage, cauliflower, or brussel sprouts (1/2 cup)	Never or <1 per month, ≥1 per month
Carrots, raw (1/2 carrot or 2–4 sticks)	Never or <1 per month, ≥1 per month
Carrots, cooked (1/2 cup)	Never or <1 per month, ≥1 per month
Corn (1 ear or 1/2 cup frozen, canned)	Never or <1 per month, ≥1 per month
Peas or lima beans (1/2 cup frozen, canned)	Never or <1 per month, ≥1 per month
Yams or sweet potatoes (1/2 cup)	Never or <1 per month, ≥1 per month
Spinach or collard greens, cooked (1/2 cup)	Never or <1 per month, ≥1 per month
Beans or lentils, baked or dried (1/2 cup)	Never or <1 per month, ≥1 per month
Yellow squash (1/2 cup)	Never or <1 per month, ≥1 per month
Eggs (1)	Never or <1 per month, ≥1 per month
Chicken or turkey (4–6 oz.)	Never or <1 per month, ≥1 per month
Bacon (2 slices)	Never or <1 per month, ≥1 per month
Hot dogs (1)	Never or <1 per month, ≥1 per month
Processed meats, e.g., sausage, salami, bologna, chorizo, etc. (piece or slice)	Never or <1 per month, ≥1 per month
Liver (3–4 oz.)	Never or <1 per month, ≥1 per month
Hamburger (1 patty)	Never or <1 per month, ≥1 per month
Beef, pork, lamb or cabrito as a sandwich or mixed dish, e.g., stew, casserole, lasagna, etc.	Never or <1 per month, ≥1 per month
Beef, pork, lamb or cabrito as a main dish, e.g., steak, roast, ham, etc. (4–6 oz.)	Never or <1 per month, ≥1 per month
Fish (3–5 oz.)	Never or <1 per month, ≥1 per month
Chocolate (1 oz.)	Never or <1 per month, ≥1 per month
Candy without chocolate (1 oz.)	Never or <1 per month, ≥1 per month
Pie (slice)	Never or <1 per month, ≥1 per month
Cake (slice)	Never or <1 per month, ≥1 per month
Cookies (1)	Never or <1 per month, ≥1 per month
White bread (slice), including pita bread	Never or <1 per month, ≥1 per month
Dark bread (slice), including wheat pita bread	Never or <1 per month, ≥1 per month
French fried potatoes (4 oz.)	Never or <1 per month, ≥1 per month
Potatoes, baked, boiled (1) or mashed (1 cup)	Never or <1 per month, ≥1 per month
Rice or pasta, e.g., Spanish rice, spaghetti, noodles, etc. (1 cup)	Never or <1 per month, ≥1 per month
Potato chips or corn chips (small bag or 1 oz.)	Never or <1 per month, ≥1 per month
Nuts (small packet or 1 oz.)	Never or <1 per month, ≥1 per month
Peanut butter (1 Tbs)	Never or <1 per month, ≥1 per month
Oil and vinegar dressing, e.g., Italian (1 Tbs)	Never or <1 per month, ≥1 per month
Cantaloupe (1/4 melon)	Never or <1 per month, ≥1 per month
Avocado (1) or guacamole (1 cup)	Never or <1 per month, ≥1 per month
Raw chile peppers, jalapeno (1)	Never or <1 per month, ≥1 per month
Salsa (1 cup)	Never or <1 per month, ≥1 per month
Chicken livers (1 oz.)	Never or <1 per month, ≥1 per month
Organ meats, Barbacoa, Menudo, sweetbreads, tongue, intestines (3–4 oz.)	Never or <1 per month, ≥1 per month
Tortilla (1)	Never or <1 per month, ≥1 per month
Refried Beans (1 cup)	Never or <1 per month, ≥1 per month
Maternal age at delivery	Continuous (years)
Father age at delivery	Continuous (years)
Number of previous live births	Continuous
Gravidity	Continuous
Number of people supported with household income	Continuous
Time spent per shower	Continuous (min)
Time spent per bath	Continuous (min)
Number of jobs from B1-P1	Continuous
Diet quality index	Continuous
Alanine	Continuous (g)
Betaine	Continuous (mg)
Calcium	Continuous (mg)
Alpha-carotene	Continuous (μg)
Beta-carotene	Continuous (μg)
Total carbohydrate	Continuous (g)
Total choline	Continuous (mg)
Copper	Continuous (mg)
Cystine	Continuous (g)
Total lipid	Continuous (g)
Iron	Continuous (mg)
Folate	Continuous (μg, dietary folate equivalents)
Glycemic index	Continuous
Lutein and zeaxanthin	Continuous (μg)
Methionine	Continuous (g)
Magnesium	Continuous (mg)
Niacin	Continuous (mg)
Total protein	Continuous (g)
Retinol	Continuous (μg)
Riboflavin	Continuous (mg)
Selenium	Continuous (μg)
Thiamin	Continuous (mg)
Vitamin E	Continuous (mg, alpha-tocopherol)
Vitamin A	Continuous (international units)
Vitamin A	Continuous (μg, retinoic acid equivalents)
Vitamin B12	Continuous (μg)
Vitamin B6	Continuous (mg)
Vitamin C	Continuous (mg)
Zinc	Continuous (mg)
Caffeine from coffee	Continuous (mg)
Caffeine from tea	Continuous (mg)
Caffeine from soda	Continuous (mg)
Total caffeine	Continuous (mg)

Abbreviations: B1, month before conception; P1, first month of pregnancy; P2, second month of pregnancy; P3, third month of pregnancy.