Table 1 Associations between fetal sex and maternal pregnancy outcomes

 Andersen et al. 2016 [15]

Logistic regression

F

0..69 (0..38–1..25)

0.22

 Baibergenova et al. 2006 [16]

Logistic regression

F

1.06 (0.55–2.50)

0.87

 Campbell et al. 1983 [17]

Logistic regression

M

1.18 (1.09–1.27)

< 0.0001

 Chien et al. 2011 [18]

Logistic regression

M

0.97 (0.96–0.98)

< 0.0001

 Engel et al. 2008 [19]

Chi-square

Total

M

1.04 (0.94–1.14)

0.46

Mild

M

1.04 (0.94–1.16)

0.44

Moderate

F

0.99 (0.80–1.24)

0.95

Severe

F

0.94 (0.62–1.42)

0.76

 Favilli et al. 2013 [20]

Logistic regression

F

1.69 (0.63–4.57)

0.43

Maternal age > 40 years, weight gain, BMI, gestational diabetes

0.98 (0.43–2.25)

0.97

 Hou et al. 2014 [21]

Logistic regression

F

0.97 (0.91–1.02)

0.25

 Juberg et al. 1976 [22]

Chi-square

M

0.03

Li et al. 2016 [23]

Logistic regression

F

0.97 (0.78–1.21)

0.79

 Makhseed et al. 1998 [24]

Logistic regression

Total

M

1.01 (0.86–1.20)

0.87

Primiparous

F

0.87 (0.65–1.17)

0.36

Multiparous

M

1.09 (0.89–1.33)

0.42

 Persson et al. 2014 [25]

Logistic regression

Healthy population

M

1.03 (1.01–1.06)

0.003

Gestational diabetes

M

1.08 (0.93–1.26)

0.31

Diabetes mellitus type I

F

0.93 (0.79–1.09)

0.35

Diabetes mellitus type II

F

0.83 (0.44–1.57)

0.56

 Ricart et al. 2009 [76]

Logistic regression

M

1.22 (0.91–1.63)

0.19

 Sheiner et al. 2004 [26]

Logistic regression

=

1.00 (0.95–1.05)

0.96

 Shiozaki et al. 2011 [27]

Logistic regression

F

0.88 (0.83–0.92)

< 0.0001

 Sykes et al. 2014 [77] 

Logistic regression

M

1.33 (0.67–2.63)

0.42

 Tundidor et al. 2012 [28]

Relative risk

F

0.81 (0.55–1.20)

NR

 Valvi et al. 2017 [109]

Logistic regression

M

1.03 (0.58–1.85)

0.91

 Verburg et al. 2016 [29]

Relative risk

Total

M

1.05 (1.03–1.07)

NR

25–29 weeks

F

0.69 (0.58–0.81)

NR

30–33 weeks

F

0.87 (0.79–0.97)

NR

34–36 weeks

F

0.93 (0.87–0.98)

NR

37–39 weeks

M

1.06 (1.04–1.09)

NR

40–42 weeks

M

1.07 (1.04–1.11)

NR

 Zheng et al. 2016 [30]

Logistic regression

F

0.54 (0.26–1.14)

0.11

 Aibar et al. 2012 [31]

Logistic regression

F

0.99 (0.65–1.49)

0.94

 Aliyu et al. 2012 [32]

Logistic regression

F

0.90 (0.79–1.03)

0.12

 Andersen et al. 2016 [15]

Logistic regression

Total

F

0.95 (0.69–1.31)

0.76

Preterm

F

1.04 (0.42–2.56)

0.94

Term

M

1.22 (0.85–1.74)

0.29

 Basso et al. 2001 [33]

Logistic regression

M

0.94 (0.92–0.97)

< 0.05

 Brettel et al. 2008 [34]

Logistic regression

F

1.17 (1.01–1.35)

0.03

 Campbell et al. 1983 [17]

Logistic regression

F

1.08 (0.94–1.24)

0.3

 Choong et al. 1995 [35]

Logistic regression

F

1.45 (1.22–1.71)

< 0.0001

 Chu et al. 2014 [36]

Logistic regression

M

0.60 (0.19–1.83)

0.39

 Hadar et al. 2017 [37]

Logistic regression

F

0.99 (0.68–1.43)

0.95

 Hou et al. 2014 [21]

Logistic regression

F

0.95 (0.88–1.02)

0.13

 Juberg et al. 1976 [22]

Chi-square

M

0.06

 Khalil et al. 2013 [38]

Logistic regression

Total

M

1.04 (0.91–1.19)

0.57

Preterm

F

1.53 (1.07–2.20)

0.02

Term

M

1.08 (0.93–1.25)

0.31

Postterm

M

3.46 (1.40–8.53)

0.007

 Lao et al. 2011 [39]

Logistic regression

F

0.92 (0.81–1.06)

0.26

 Lao et al. 2017 [40]

Logistic regression

M

1.56 (1.41–1.73)

<0.0001

 Li et al. 2016 [23]

Logistic regression

F

0.66 (0.45–0.98)

0.04

 Lisonkova et al. 2013 [41]

Cox regression

< 34 weeks

M

1.10 (1.07–1.14)

NR

NR

1.10 (1.06–1.14)

NR

> 34 weeks

M

1.10 (1.07–1.14)

NR

NR

1.10 (1.06–1.14)

NR

 Liu et al. 2016 [42]

Logistic regression

Total

0.96 (0.88–1.04)

0.31

Preterm

1.15 (1.00–1.32)

0.046

 Makhseed et al. 1998 [24]

Logistic regression

Total

F

0.92 (0.68–1.24)

0.57

Nulliparous

F

0.74 (0.49–1.10)

0.13

Multiparous

M

1.20 (0.76–1.90)

0.43

 Masoumi et al. 2017 [43]

Logistic regression

Total

M

1.09 (0.90–1.31)

0.40

Severe

M

1.43 (0.81–2.51)

0.21

 Morsing et al. 2018 [44]

Logistic regression

F

0.80 (0.59–1.09)

0.16

 Myers et al. 2015 [45]

Logistic regression

=

0.94 (0.65–1.36)

0.74

 Peled et al. 2013 [46]

Logistic regression

M

1.79 (0.42–7.56)

0.43

 Persson et al. 2014 [25]

Logistic regression

Healthy population

M

1.03 (1.01–1.06)

0.003

Gestational diabetes

M

1.08 (0.93–1.26)

0.31

Diabetes mellitus type I

F

0.93 (0.79–1.09)

0.35

Diabetes mellitus type II

F

0.83 (0.44–1.57)

0.56

 Quiñones et al. 2005 [47]

Logistic regression

M

1.15 (0.77–1.70)

0.5

 Reynolds et al. 2012 [48]

Logistic regression

Total

F

0.85 (0.71–1.02)

0.08

Preterm

F

1.25 (0.79–1.97)

0.34

Term

F

0.86 (0.71–1.04)

0.13

 Roy et al. 2015 [49]

Logistic regression

Total

M

1.28 (0.72–2.29)

0.4

Preterm

M

0.77 (0.33–1.81)

0.55

Term

M

1.28 (0.66–2.46)

0.46

 Sharifzadeh et al. 2012 [50]

F

0.88 (0.33–2.35)

0.8

 Sheiner et al. 2004 [26]

Logistic regression

=

1.00 (0.95–1.05)

0.96

 Shiozaki et al. 2011 [27]

Chi-square

Pre-eclampsia

F

0.84 (0.79–0.89)

< 0.001

Pre-eclampsia with fetal death

M

1.21 (0.70–1.48)

0.95

Severe pre-eclampsia

F

1.21 (1.10–1.33)

0.001

Severe pre-eclampsia with fetal death

F

1.14 (0.67–1.93)

0.63

 Sykes et al. 2014 [77]

Logistic regression

M

1.27 (0.64–2.51)

0.49

 Taylor et al. 2018 [51]

Logistic regression

F

0.94 (0.67–1.30)

0.70

 Taylor et al. 2018 [51]

Logistic regression

PE overall

F

0.89 (0.64–1.24)

0.69

Term (> 37 weeks)

F

0.92 (0.65–1.30)

0.63

Preterm (<37 weeks)

F

0.72 (0.37–1.39)

0.32

Very preterm (<34 weeks)

F

0.38 (0.13–1.07)

0.07

 Toivanen et al. 1970 [52]

Logistic regression

M

1.20 (1.06–1.37)

0.005

 Trudel et al. 2015 [53]

Logistic regression

M

1.01 (0.95–1.07)

0.82

 Vatten et al. 2004 [54]

Logistic regression

Total

M

1.05 (1.03–1.07)

< 0.0001

Preterm (< 37 weeks)

F

1.17 (1.11–1.22)

< 0.0001

Term (37–42 weeks)

M

1.06 (1.04–1.08

< 0.0001

Postterm (> 42 weeks)

M

1.07 (0.96–1.18)

0.23

25–29 weeks

F

1.55 (1.31–1.83)

< 0.0001

30–33 weeks

F

1.33 (1.21–1.46)

< 0.0001

34–36 wls

F

1.07 (1.01–1.14)

0.03

37–39 weeks

F

0.98 (0.85–1.01)

0.18

40–42 weeks

M

1.10 (1.07–1.13)

< 0.0001

 Verburg et al. 2016 [29]

Relative risk

Total

M

1.05 (1.03–1.07)

NR

25–29 weeks

F

0.69 (0.58–0.81)

NR

30–33 weeks

F

0.87 (0.79–0.97)

NR

34–36 weeks

F

0.93 (0.87–0.98)

NR

37–39 weeks

M

1.06 (1.04–1.09)

NR

40–42 weeks

M

1.07 (1.04–1.11)

NR

 Wandabwa et al. 2010 [79]

Logistic regression

F

0.65 (0.45–0.95)

0.03

 Weinberg et al. 2017 [55]

Logistic regression

Total

M

1.01 (0.98–1.04)

0.71

Term (> 37 weeks)

M

1.05 (1.01–1.08)

0.01

Preterm (<37 weeks)

F

0.89 (0.84–0.94)

0.0001

 Zheng et al. 2016 [30]

Logistic regression

Total

F

0.49 (0.27–0.89)

0.02

Mild

F

0.65 (0.30–1.43)

0.29

Severe

F

2.60 (1.18–5.73)

0.02

 Aibar et al. 2012 [31]

Logistic regression

M

1.54 (0.50–4.72)

0.45

 Aliyu et al. 2012 [32]

Logistic regression

F

0.92 (0.42–2.01)

0.83

 Campbell et al. 1983 [17]

Logistic regression

F

0.89 (0.35–2.32)

0.82

 Chien et al. 2011 [18]

Logistic regression

=

1.00 (0.97–1.04)

0.89

 Hou et al. 2014 [21]

Chi-square

M

0.13

 Llopez-Lera et al. 1990 [82]

Chi-square

M

< 0.05

 Persson et al. 2014 [25]

Logistic regression

Healthy population

M

1.03 (1.01–1.06)

0.003

Gestational diabetes

M

1.08 (0.93–1.26)

0.31

Diabetes mellitus type I

F

0.93 (0.79–1.09)

0.35

Diabetes mellitus type II

F

0.83 (0.44–1.57)

0.56

 Wandabwa et al. 2010 [79]

Logistic regression

F

0.65 (0.45–0.95)

0.03

 Aibar et al. 2012 [31]

Logistic regression

M

1.21 (1.06–1.37)

0.0034

 Breschi et al. 1993 [56]

Logistic regression

F

0.96 (0.36–2.52)

0.93

 Cosson et al. 2016 [57]

Logistic regression

=

1.00 (0.93–1.08)

0.96

 Ehrlich et al. 2012 [58]

Logistic regression

M

1.02 (0.99–1.05)

NR

Maternal ethnicity

1.02 (0.99–1.05)

NR

Maternal ethnicity. education and age

1.02 (0.99–1.05)

NR

 Engel et al. 2008 [19]

Logistic regression

M

1.07 (0.85–1.36)

0.54

 Favili et al. 2013 [20]

Logistic regression

M

2.36 (0.58–9.61)

0.37

Maternal age > 40 years, BMI, weight gain, gestational hypertension

0.95 (0.37–2.46)

0.92

 Heckbert et al. 1988 [59]

Logistic regression

F

0.97 (0.77–1.21)

0.79

 Hou et al. 2014 [21]

Logistic regression

M

1.01 (0.96–1.07)

0.61

 Janssen et al. 1996 [60]

Logistic regression

M

1.02 (0.96–1.08)

0.5

 Kale et al. 2005 [61]

Logistic regression

M

1.64 (1.12–2.40)

0.01

 Khalil et al. 2013 [38]

Logistic regression

M

1.41 (1.15–1.72)

< 0.001

 Lao et al. 2011 [39]

Logistic regression

M

1.05 (0.99–1.12

0.12

 Lao et al. 2017 [40]

Logistic regression

M

1.06 (1.01–1.11)

0.08

 Lawlor et al. 2009 [84]

Logistic regression

M

1.61 (0.92–2.81)

0.09

 Liu et al. 2016 [42]

Logistic regression

M

1.08 (1.00–1.16)

0.048

 Macaulay et al. 2018 [86]

Logistic regression

M

1.16 (0.73–1.84)

0.53

 Oken et al. 2016 [62]

Logistic regression

M

1.39 (0.81–2.36)

0.23

 Okereke et al. 2002 [63]

Logistic regression

M

1.39 (0.81–2.36)

0.23

 Peled et al. 2013 [46]

Logistic regression

M

3.24 (0.65–16.22)

0.15

 Retnakaran et al. 2015 [64]

Logistic regression

M

1.03 (1.00–1.05)

0.047

 Retnakaran et al. 2015 [64]

Logistic regression

M

1.24 (0.92–1.67)

0.16

 Ricart et al. 2009 [76]

Logistic regression

M

1.05 (0.91–1.22)

0.17

 Sheiner et al. 2004 [26]

Logistic regression

M

1.07 (1.01–1.12)

0.01

 Spellacy et al. 1985 [65]

Chi-square

M

NS

 Strutz et al. 2018 [66]

Logistic regression

M

1.80 (0.40–8.18)

0.45

 Trudel et al. 2015 [53]

Logistic regression

F

0.96 (0.90–1.04)

0.32

 Verburg et al. 2016 [29] 

RR

M

1.04 (1.01–1.07)

NR

 Xiao et al. 2014 [67]

Logistic regression

M

1.29 (0.58–2.89)

0.53

 Aliyu et al. 2012 [32]

Logistic regression

F

0.98 (0.87–1.12)

0.8

 Brettel et al. 2008 [34]

Logistic regression

M

1.29 (0.97–1.71)

0.08

 Engel et al. 2008 [19]

Logistic regression

F

0.53 (0.28–0.99)

0.049

 Hou et al. 2014 [21]

Logistic regression

F

0.98 (0.83–1.15)

0.76

 Jakobovits et al. 1988 [68]

Chi-square

Total

M

NS

17–20 years

M

< 0.001

21–25 years

M

< 0.01

26–30 years

F

NS

31–35 years

M

< 0.05

36–40 years

M

< 0.05

41–42 years

=

NS

 Lopez-Llera et al. 1990 [82]

Logistic regression

M

0.94 (0.54–1.66)

0.84

 Peled et al. 2013 [46]

Logistic regression

M

2.90 (0.76–11.03)

0.12

 Raissanen et al. 2013 [110] 

Logistic regression

Total

M

1.19 (1.12–1.26)

< 0.0001

Nulliparous

M

1.23 (1.12–1.36)

< 0.0001

NR

1.36 (1.23–1.51)

Multiparous

M

1.16 (1.08–1.26)

0.001

NR

1.38 (1.27–1.50)

 Schildberger et al. 2016 [69]

Logistic regression

F

0.84 (0.81–0.87)

< 0.0001

 Sheiner et al. 2002 [70]

Logistic regression

F

0.98 (0.78–1.24)

0.88

 Sheiner et al. 2004 [26]

Logistic regression

M

1.15 (0.89–1.49)

0.28

 Tikkanen et al. 2013 [90]

Logistic regression

M

1.18 (1.11–1.25)

< 0.0001

 Wandabwa et al. 2005 [91]

Logistic regression

M

2.20 (1.20–4.90)

< 0.01

Distance to hospital. age, type of house, hypertension, previous caesarean section, previous stillbirth

1.90 (1.00–3.80)

NR

 Weissmann–Brenner et al. 2015 [71]

Logistic regression

Total

M

1.20 (0.77–1.87)

0.42

Age < 40 years

M

1.14 (0.73–1.79)

0.56

Age > 40 years

M

5.08 (0.24–106.0)

0.29

 Favili et al. 2013 [20] 

Logistic regression

Total

M

1.12 (0.34–3.72)

0.85

Age ≥ 40 years

M

2.10 (0.40–11.01)

0.38

Age < 40 years

F

0.35 (0.04–3.37)

0.36

 Weissmann–Brenner et al. 2015 [71]

Logistic regression

Total

M

1.20 (0.88–1.65)

0.25

Age ≥ 40 years

M

1.16 (0.84–1.61)

0.35

Age < 40 years

M

4.07 (0.45–36.5)

0.21

 Liu et al. 2016 [42]

Logistic regression

F

0.91 (0.83–0.99)

0.0046

 Byrne et al. 1987 [72]

Risk ratio

Total

M

< 0.05

Morphological normal

M

< 0.05

Morphological abnormal

F

> 0.05

 Cheng et al. 2014 [73]

Risk ratio

F

< 0.001

 Del Fabro et al. 2011 [74]

Risk ratio

Total

F

< 0.05

4–10 weeks

F

< 0.001

11–15 weeks

F

0.07

16–20 weeks

F

0.06