The Association Between Coffee and Tea Consumption During Pregnancy and Preterm Delivery: Case–Control Study

Figures & data

Table 1 Differences in Categorical Demographic Characteristics Between Cases and Controls

Total, n (Percent)		Preterm Delivery
		Yes, n (%)	Normal, n (%)	P value
Ethnic group
White	1066 (96.9)	296 (94.3)	770 (98.0)	0.001
Black	34 (3.1)	18 (5.7)	16 (2.00)
Education level
Less than high school	450 (40.7)	126 (40.1)	324 (40.9)	0.216
High school	342 (30.9)	88 (28.0)	254 (32.1)
Above high school	314 (28.4)	100 (31.8)	214 (27.0)
Occupation
Housewife	996 (90.1)	282 (89.8)	714 (90.2)	0.864
Worker	110 (9.9)	32 (10.2)	78 (9.8)
Smoking
No  Yes	1082 (98.0) 22 (2.0)	308 (98.1) 6 (1.9)	774 (98.0) 16 (2.0)	1.000
Passive smoking
No	608 (55.0)	156 (49.7)	452 (57.1)	0.026
Yes	498 (45.0)	158 (50.3)	340 (42.9)
Emotional state during pregnancy
Happiest time of life	222 (20.1)	54 (17.2)	168 (21.3)	0.008
Happy with few problems	632 (57.2)	170 (54.1)	462 (58.5)
Unhappy	250 (22.6)	90 (28.7)	160 (20.3)
Coffee consumption/day
No intake	666 (60.3)	180 (57.3)	486 (61.5)	0.391
1 cup	224 (20.3)	72 (22.9)	152 (19.2)
2 cups	128 (11.6)	40 (12.7)	88 (11.1)
≥3 cups	86 (7.8)	22 (7.0)	64 (8.1)
Tea consumption (cup/day)
No intake	496 (44.9)	132 (42.0)	364 (46.1)	0.058
1 cup	208 (18.8)	68 (21.7)	140 (17.7)
2 cups	182 (16.5)	42 (13.4)	140 (17.7)
≥3 cups	218 (19.7)	72 (22.9)	146 (18.5)
Analgesics intake
No	868 (78.4)	252 (80.1)	616 (77.8)	0.366
Yes	238 (21.5)	62 (19.9)	176 (22.2)
Parity
No	294 (26.9)	110 (35.0)	184 (23.2)	0.005
Yes	812 (73.1)	204 (65.0)	608 (76.8)
Inter-pregnancy interval
<2 years	126 (11.4)	44 (14.0)	82 (10.4)	0.084
≥2 years	980 (88.6)	270 (86.0)	710 (89.6)

Table 2 Differences in Categorical Medical Variables Between Cases and Controls

Total, n (Percent)		Preterm Delivery
		Yes, n (%)	Normal, n (%)	P value
Blood group
A	410 (27.7)	104 (33.1)	306 (38.7)	0.322
B	154 (19.9)	48 (15.3)	106 (13.4)
AB	78 (6.4)	28 (8.9)	50 (6.3)
O	406 (40.4)	118 (37.6)	288 (36.5)
Unknown	56 (5.7)	16 (5.1)	40 (5.1)
DM
No	1066 (96.4)	292 (93.0)	774 (97.7)	0.005
Yes	40 (3.6)	22 (7.0)	18 (2.3)
Hypertension
No	924 (83.7)	234 (74.5)	690 (87.3)	0.005
Yes	180 (16.3)	80 (25.5)	100 (12.7)
History of preterm delivery
No	1024 (92.8)	256 (81.5)	768 (97.2)	0.005
Yes	80 (7.2)	58 (18.5)	22 (2.8)
History of low weight delivery
No	1006 (91.1)	262 (83.4)	744 (94.2)	0.005
Yes	98 (8.9)	52 (16.6)	46 (5.8)
History of caesarian delivery
No	858 (77.7)	240 (76.4)	618 (78.2)	0.518
Yes	246 (22.3)	74 (23.6)	172 (21.8)
Vaginal bleeding during pregnancy
No	1090 (98.7)	308 (98.1)	782 (99.0)	0.229
Yes	14 (1.3)	6 (1.9)	8 (1.0)
Pregnancy following sub-fertility treatment
No	1090 (98.7)	302 (96.2)	788 (99.7)	0.005
Yes	14 (1.3)	12 (3.8)	2 (0.3)
Family history of preterm deliveries
No	1094 (99.1)	306 (97.5)	788 (99.7)	0.005
Yes	10 (0.9)	8 (2.5)	2 (0.3)
Family history of low weight deliveries
No	1096 (99.3)	308 (98.1)	788 (99.7)	0.003
Yes	8 (0.7)	6 (1.9)	2 (0.3)
Urinary tract infection
No	912 (82.6)	250 (79.6)	662 (83.8)	0.098
Yes	192 (17.4)	64 (20.4)	128 (16.2)
Abortion
No	786 (71.1)	198 (63.1)	588 (74.2)	0.005
Yes	320 (28.9)	116 (36.9)	204 (25.8)

Table 3 Differences in Drugs Used During Pregnancy Between Cases and Controls

Total, n (Percent)		Preterm Delivery
		Yes, n (%)	Normal, n (%)	P value
Iron intake
No	294 (26.6)	96 (30.6)	198 (25.0)	0.059
Yes	812 (73.4)	218 (69.4)	594 (75.0)
Folic acid intake
No	1048 (94.8)	288 (91.7)	760 (96.0)	0.004
Yes	58 (5.2)	26 (8.3)	32 (4.0)
Calcium intake
No	1070 (96.7)	304 (96.8)	766 (96.7)	0.934
Yes	36 (3.3)	10 (3.2)	26 (3.3)
Analgesics intake
No	868 (78.4)	252 (80.1)	616 (77.8)	0.366
Yes	238 (21.5)	62 (19.9)	176 (22.2)
Antibiotics intake
No	874 (79.0)	244 (77.7)	630 (79.5)	0.498
Yes	232 (21.0)	70 (22.3)	162 (20.5)
Baby aspirin intake
No	1042 (94.2)	292 (93.0)	750 (94.7)	0.274
Yes	64 (5.8)	22 (7.0)	42 (5.3)

Table 4 Differences in Continuous Demographic Characteristics Between Cases and Controls

Total Mean ± SD		Preterm Delivery
		Yes Mean ± SD	No Mean ± SD	p value
Age (years)	29.18 ± 6.11	29.61 ± 5.96	28.47 ± 5.48	0.003
Total family income (JD/month)	210.45 ± 136.90	210.83 ± 133.95	210.80 ± 146.05	0.997
Pre-pregnancy weight (kg)	63.32 ± 11.83	65.27 ± 12.50	64.05 ± 11.40	0.133
Weight at delivery (kg)	74.87 ± 11.90	76.23 ± 12.70	74.98 ± 11.81	0.133
Height (cm)	161.95 ± 4.10	161.88 ± 4.76	161.99 ± 4.54	0.733
Total antenatal visits	8.33 ± 2.62	8.32 ± 2.93	8.34 ± 2.90	0.920
Coffee consumption (cup/day)	0.74 ± 1.30	0.75 ± 1.23	0.73 ± 1.86	0.773
Tea consumption (cup/day)	1.35 ± 174	1.47 ± 1.76	1.29 ± 1.61	0.115

Table 5 Adjusted Odds Ratios for Predictor Variables Associated with Preterm Delivery

Predictor	Preterm Delivery
	Adjusted OR	95% CI	P value
Coffee consumption (cup/day)
No intake	1.00
1 cup	1.32	0.89-1.96	0.164
2 cups	1.47	0.90-2.38	0.121
>3 cups	0.72	0.40-1.29	0.271
Tea consumption (cup/day)
No intake	1.00
1 cup	1.12	0.79-1.82	0.394
2 cups	0.89	0.45-1.14	0.157
>3 cups	1.43	0.88-1.94	0.195
Emotional state during pregnancy
Happiest time of life	1.00
Happy with few problems	1.63	1.09-2.44	0.018
Unhappy	2.35	1.49-3.72	0.005
Parity
Yes	1.00
No	3.82	2.58-5.64	0.005
Abortion
No	1.00
Yes	1.69	1.21-2.35	0.002
Inter-pregnancy interval (years)
≥2	1.00
<2	1.72	1.10-2.69	0.017
Color
White	1.00
Black	2.87	1.35-6.10	0.006
Family history of preterm delivery
No	1.00
Yes	2.45	1.33-4.66	0.004
DM
No	1.00
Yes	2.22	1.06-4.66	0.035
Pregnancy resulted from sub-fertility treatment
No	1.00
Yes	12.14	2.39-61.62	0.003
Iron consumption
No	1.46	1.06 −2.03	0.022
Yes	1.00
Folic acid consumption
No	1.00
Yes	2.45	1.33-4.52	0.004
Age	1.05	1.02–1.08	0.001