Table 1 Studies examining the association between COVID-19 lockdown and premature births and low birth weight rates

 Ashish et al. (2020)

Cohort

Nepal

SUSTAIN¹and REFINE¹ studies

Jan 1-May 30, 2020

Singletons

<  37 weeks¹

167

<  0.0001 (0.160, 0.174)

<  37 weeks

200

< 0.0001 (0.178, 0204)

aRR = 1.3

0.0016 (1.2, 1.4)

16.5% increase

<  2500 g¹

111

N/A

<  2500 g

105

N/A

N/A

0.37

0.1% NS decrease

 Been (2020) [9]

Quasi experimental

The Netherlands

Praeventis (RIVM)

Oct 9, 2010-Jul 16, 2020

Singletons

<  37 weeks

+/− 2 months from Mar 9¹

N/R

N/R

<  37 weeks

+/−  2 months from Mar 9

N/R

N/R

OR = 0.77

0.002 (0.66, 0.91)

Decrease

<  37 weeks

+/− 3 months from Mar 9¹

N/R

N/R

<  37 weeks

+/−  3 months from Mar 9

N/R

N/R

OR = 0.85

0.028 (0.73, 0.98)

Decrease

<  37 weeks

+/− 4 months from Mar 9¹

N/R

N/R

<  37 weeks

+/−  4 months from Mar 9

N/R

N/R

OR = 0.84

0.023 (0.73, 0.97)

Decrease

<  37 weeks

+/− 4 months from Mar 15

N/R

N/R

<  37 weeks

+/− 4 months from Mar 15

N/R

N/R

OR = 0.96

(0.83–1.10)

NS decrease

<  37 weeks

+/− 4 months from Mar 23

N/R

N/R

<  37 weeks

+/− 4 months from Mar 23

N/R

N/R

OR = 1.03

(0.90–1.18)

NSincrease

 Hedermann et al. (2020)

Cohort

Denmark

National Screening Biobank (DNSB)

Mar 12-Apr 14, 2015–2020

Singletons

<  28 weeks

2.19

0.003

<  28 weeks

0.19

< 0.001

OR = 0.09

< 0.001 (0.01, 0.40)

90.0% decrease

28–31 weeks

5.57

N/A

28–31 weeks

6.62

N/A

OR = 1.11

0.589 (0.75, 1.61)

15.9% NS increase

32–36 weeks

42.8

N/A

32–36 weeks

41.84

N/A

OR = 0.98

0.742 (0.84, 1.13)

2% NS decrease

 Khalil et al. (2020) [10]

Cohort

United Kingdom

St. George’s University Hospital

Oct 1-Jun 21, 2019–2020

Singletons, Twins & Triplets

<  37 weeks

68

N/A

<  37 weeks

76

N/A

cOR = 1.11

0.46 (−2.43, 1.07)

10.5% NS increase

<  34 weeks

25

N/A

<  34 weeks

37

N/A

cOR = 1.46

0.07 (−0.05, 2.30)

32.4% NS increase

 Philip et al. (2020) [11]

Cohort

Ireland

UMHL¹

VON¹

CSO¹

Jan 1-Apr 31, 2001–2020

Singletons & Multiple births

<  1500 g¹

8.18

(7.21, 9.29)

<  1500 g

2.17

0.022 (1.21, 11.75)

Rate ratio = 3.77

0.022 (1.21, 11.75)

73.5% decrease

< 1000 g¹

2.17

(2.43, 3.70)

< 1000 g

0

N/A

N/A

N/A

100% NS decrease

 Matheson et al. (2021) [12, 13]

Cohort

Australia

3 maternity hospitals

July-Sep

2019–2020

Singleton and multiple

< 37 weeks

101

N/A

< 37 weeks

83

N/A

OR = 0.81

(0.67–0.98)

Decrease

< 34 weeks

36

N/A

< 34 weeks

26

N/A

OR = 0.71

(0.51–0.98)

Decrease

< 28 weeks

8

N/A

< 28 weeks

4

N/A

OR = 0.46

(0.21–0.99)

Decrease

 De Curtis et al. (2020) [14]

Cohort

Italy

Lazio (nationwide)

Mar-May 2019–2020

Singletons

< 32 weeks

5.5

N/A

< 32 weeks

7.9

N/A

N/A

0.06

NS increase

32–36 weeks

59.3

N/A

32–36 weeks

46.2

N/A

N/A

< 0.001

Decrease

 Justman et al. (2020) [15]

Cross sectional

Israel

Tertiary center

Mar-Apr 2019–2020

Singleton and multiple

< 37 weeks

65

N/A

< 37 weeks

64

N/A

N/A

0.96

NS decrease

 Caniglia et al. (2021) [16]

Cohort

Botswana

Tsepamo study

Jan1-July20

2019–2020

Singletons

< 32 weeks

−0.21%

(−0.67, 0.25%)

< 32 weeks

−0.47%

(% reduction)

(−1.15, 0.21%)

−0.26%

(% reduction)

(−0.80, 0.27%)

NS decrease

< 37 weeks

0.25%

(−0.66%,1.15%)

< 37 weeks

−1.27%

(% reduction)

−2.71%,0.1%)

−1.52%

(% reduction)

(−3.14, 0.10%)

NS decrease

 Arnaez et al. (2021) [17]

Retrospective

Spain

13 hospitals of the Castilla-y-Léon region

Jan 1-June 21, 2015–2020

Singletons

32–36 weeks

57.4

(5.56–5.92)

32–36 weeks

56.6

(4.83–6.48)

N/A

N/A

NS decrease

28–31 weeks

6

(0.54–0.66)

28–31 weeks

4.7

(0.22–0.71)

N/A

N/A

NS decrease

23–27 weeks

2.8

(0.24–0.32)

23–27 weeks

3.7

(0.15–0.58)

OR = 1.38

0.0438(0.61–3.12)

Increase

< 1500 g

9.8

(0.91–0.105)

< 1500 g

9.8

(0.63–1.33)

N/A

N/A

NS change

< 1000 g

3.4

(0.29–0.38)

< 1000 g

4.6

(0.22–0.70)

OR = 1.19

0.724(0.44–3.23)

NS increase

 Huseynova et al. (2021) [18]

Cross sectional

Saudi Arabia

Public Sector Children Hospital - King Saud Medical City (KSMC)

Mar 1- June 30, 2017–2020

Singleton and multiple

< 28 weeks

19.87

N/A

< 28 weeks

13

N/A

RR = 63.8%

0.047

36.2% decrease

28–31 weeks

29.13

N/A

28–31 weeks

31.2

N/A

RR = 101.20%

0.398

NS increase

32–36 weeks

144.13

N/A

32–36 weeks

106.6

N/A

RR = 73.66%

0.0004

26.34% decrease

 Kirchengast et al. (2021) [19]

Retrospective medical record-based single-centre

Austria

Viennese Danube Hospital and Statistics Austria

Jan 1- July 31, 2017–2020

Singleton

< 1000 g

7.2

N/A

< 1000 g

2.9

N/A

OR = 2.48

0.35–17.50

Decrease

< 1500 g

18

N/A

< 1500 g

8.9

N/A

OR = 2.05

0.63–6.67

Decrease

1500-2500 g

54.2

N/A

1500-2500 g

38.9

N/A

OR = 1.41

0.76–2.62

Decrease

< 32 weeks

28.9

N/A

< 32 weeks

14.9

N/A

OR = 1.93

(0.76–4.79)

Decrease

32–36 weeks

54.2

N/A

32–36 weeks

62.9

N/A

OR = 1.01

(0.97–1.05)

Increase

 Gallo et al. (2021)

Retrospective

Australia

Mater Mothers’ electronic healthcare records database

March 16–May 1, 2013–2020

Singletons

23–27 weeks

6.70

N/A

23–27 weeks

8.35

N/A

aOR = 1.21

(0.69–4.20)

NS increase

28–31 weeks

10.46

N/A

28–31 weeks

5.97

N/A

aOR = 0.55

(0.22–1.75)

NS decrease

32–26 weeks

59.51

N/A

32–26 weeks

34.61

N/A

aOR = 0.57

(0.35–0.80)

Decrease