Table 1 Studies included in the systematic review

Kalkwarf et al., 1997 [2]

Cincinnati, USA

Women (20 to 36 years old) with low or moderate calcium intake (≤ 800 mg/day), breastfeeding and offering artificial formula

326

Laskey et al., 1998 [1]

Cambridge, United Kingdom

Healthy white women (20 to 40 years old)

80

Ritchie et al., 1998 [9]

Berkeley, California, USA

Healthy women who consumed ≈1200 mg calcium/day (< 22 years or > 42 years)

14

Naylor et al., 2003 [26]

Sheffield, United Kingdom

Women who were planning to become pregnant (20 to 36 years old)

17

Glerean et al., 2010 [28]

Buenos Aires, Argentina

Primiparous and nulliparous women (21 to 40 years old)

61

Sámano et al., 2011 [29]

Mexico City, Mexico

Healthy women

72

Moller et al., 2012 [12]

Aarhus, Denmark

Healthy white women (25 to 35 years old)

228

Sawo et al., 2013 [10]

Keneba and Manduar villages in West Kiang countryside, The Gambia

Women (28.6 ± 8.4 years)

33

Lebel et al., 2014 [11]

Jerusalem, Israel

Women (20 to 46 years old)

132

Sámano et al., 2014 [30]

Mexico City, Mexico

women in the postpartum period

73

Brembeck et al., 2016 [31]

Gothenburg, Sweden

Pregnant women (25 to 40 years old)

81

Zhang et al., 2016 [5]

Guangzhou, China

Puerperal women (20 to 35 years old)

150

Cooke-Hubley et al., 2017 [32]

Newfoundland, Canada

Women who exclusively breastfed for 6 months

31

Teerapornpuntakit et al., 2017 [33]

Bangkok, Thailand

Healthy women (18 to 35 years old)

80

Cullers et al., 2019 [25]

Oakland and East Bay Area, California, USA

Women in the 16th week of pregnancy

64

Ó Breasail et al., 2020 [27]

Cambridge, United Kingdom

Healthy women (30 to 45 years old)

90