Table 2.

Description of observational studies.

References	Setting	Aims, Design	Inclusion/Exclusion Criteria	Study Population	Offspring Age at Follow-Up (Years), Sex
Observational Studies (n = 7)
Goodyer et al. 2007 [32]	St. John’s Medical College Hospital, Bangalore, India and Royal Victoria Hospital, Montreal, Canada	Aim: To determine the prevalence of maternal vitamin A deficiency and its relationship to offspring nephron endowment from normal pregnant women from Bangalore (India) and Montreal (Canada) Design: Prospective cohort.	Inclusion: Healthy women with uncomplicated pregnancies Exclusion: Mothers on vitamin A supplements, high risk and medically complicated pregnancies, twin, diabetic and growth restricted pregnancies, significant fetal structural or genetic abnormalities, fetuses with significant pyelectasis or renal anomalies and pregnancies delivered <32 weeks of gestation.	Montreal: 48 Bangalore: 46	2–6 weeks of age Numbers for each sex not specified.
El-Khashab et al. 2013 [33]	Gynecology and Obstetrics Hospital, Ain Shams University, Cairo, Egypt	Aim: To assess the Vitamin A status of a cohort of Egyptian pregnant women and their newborns and to determine the potential effect of maternal Vitamin A deficiency during pregnancy on the neonatal kidney size. Design: Cross-sectional.	Inclusion: Healthy mothers, aged 19–39 years, with singleton uncomplicated pregnancy. Full term, healthy offspring with no morbidities. Exclusion: 1. Mothers with a history of exposure to teratogens, high-risk and complicated pregnancies, multiple gestations, antenatal diagnosis of intrauterine growth restriction, renal anomalies, fetal structural abnormalities, on vitamin A supplementation. 2. Offspring born <37 weeks, birth weight <2.5 kg, birth asphyxia, congenital anomalies or dysmorphic features.	Vitamin A deficiency: serum retinol concentration ≤0.7 umol/L (n = 16) Vitamin A sufficient: serum retinol concentration >0.7 umol/L (n = 64)	≤3 days Numbers for each sex not specified.
Miliku, K. et al. 2017 [31]	Generation R study: Population-based prospective cohort study from fetal life onward in Rotterdam, Netherlands	Aim: To examine the associations of folate, vitamin B12, and homocysteine concentrations during first trimester of pregnancy and at birth with kidney outcomes in school-aged children Design: Prospective cohort study.	Inclusion: Singleton live-born children from mothers with nutritional data and with at least one kidney measurement.	4226 mothers-child pairs Maternal venous blood samples were collected in early-pregnancy (median gestational age 13.2 weeks, range 12.2–14.8 weeks). Deficient folate <7 nmol/L Normal folate ≥7 nmol/L	Median (95% range): 6.0 (5.9–6.3) Deficient folate Male (51.3%) Female (48.7%) Normal folate Male (49.9%) Female (50.1%)
Miliku, K. et al. 2016 [30]	Generation R study: Population-based prospective cohort study from fetal life onward in Rotterdam, Netherlands	Aim: To examine the associations of circulating vitamin 25-hydroxyvitamin D (25(OH)D) levels during mid-pregnancy and in cord blood at birth with childhood kidney outcomes Design: Prospective cohort study.	Inclusion: Singletons with available information on maternal vitamin D blood levels during mid-pregnancy and have measurements on kidney ultrasound, creatinine and cystatin C from blood, and albumin and creatinine from urine samples at the age of 6 years. Exclusion: Children with evidence of congenital kidney abnormalities on ultrasound examination or with abnormally high urinary albumin–creatinine ratio	4212 mothers-child pairs Maternal venous blood samples were collected in mid-pregnancy (median gestational age 20.3 weeks, range 18.5–23.3 weeks). Total 25(OH)D was reported as the sum of 25(OH)D2 and 25(OH)D3 measured in plasma. Maternal vitamin D status: severely deficient <25.0 nmol/L deficient 25–49.9 nmol/L Sufficient 50.0–74.9 nmol/L Optimal ⩾75.0 nmol/L	Median (95% range): 6.0 (5.6–7.4) Male (49.6%) Female (50.4%)
Huang et al. 2014 [27]	Chinese famine of 1959–1961	Aim: To describe the long term effects of exposure to the Chinese famine of 1959–1961 during gestation and early postnatal life on the levels of proteinuria in adulthood Design: Retrospective cohort.	Inclusion: Restricted study to women born from 1957 to 1965 and living in Hebei, Zhejiang and Jiangsu provinces. Exclusion: 18.3% of rural sample, 12.9% of urban sample due to missing data on outcome variable. Famine (<1500 calories daily per capita)	Rural: n = 51,978 (i) Pre-famine (1957–1958): n = 2050 (ii) Famine (1959–1961): n = 6396 (iii) Post-famine (1962–1963): n = 24,739 (iv) Unexposed group (1964–1965): n = 18,793 Urban: n = 4563 (i) Pre-famine (1957–1958): n = 241 (ii) Famine (1959–1961): n = 518 (iii) Post-famine (1962–1963): n = 1594 (iv) Unexposed group (1964–1965): n = 2210	Approx. 30 All female only
Painter et al. 2005 [28]	The Dutch Famine Birth Cohort study, the Netherlands	Aim: To describe the long-term effects of prenatal exposure to famine on microalbuminuria and renal function Design: Retrospective cohort.	Inclusion: Exposed: Infants born in 1945 and were exposed to famine in utero. Unexposed: Infants born before or conceived after the famine. Famine <1000 calories daily	288 (40%) of the 724 participants studied had been exposed to famine in utero. Exposed (n = 288): 3 groups; 16-week periods Early gestation: n = 65 Mid gestation: n = 104 Late gestation: n = 119 Unexposed (n = 506): Born before: n = 207 Conceived after: n = 229	Mean (95% range): 50 (48–53) Male Early: 46% Mid: 42% Late: 47% Female Early: 54% Mid: 58% Late: 53%
Miliku, K. et al. 2015 [29]	Generation R study: Population-based prospective cohort study from fetal life onward in Rotterdam, Netherlands	Aim: To assess the associations between first-trimester maternal total, animal and vegetable protein intake during pregnancy and offspring kidney outcomes at 6 years Design: Prospective cohort study.	Inclusion: 1. Living in the study area at delivery 2. Delivery between April 2002 and January 2006 Exclusion: 1. Twin pregnancies 2. Loss to follow-up 3. Withdrawal of consent	3650 mother-child pairs (78%) of the 4658 children with maternal nutritional data available and who attended follow-up at age 6 with successful kidney outcome measures	Median (95% range): 6.1 (5.6–7.3) Male (49.9%) Female (50.1%)