The associations of cola intake with adverse birth outcomes among pregnant women after assisted reproductive technology treatment and women naturally conceived: a birth cohort study

Figures & data

Figure 1. Study flow. ART, assisted reproductive technology, SC, spontaneously conceived.

Table 1. Characteristics of study population in the 1st trimester.

Variables	ART cohort	SC cohort	p
N	736	1270
Maternal age (year)	30.1 (0.1)	27.4 (0.1)	<0.001
Maternal BMI (kg/m^2)	22.8 (0.4)	21.4 (0.1)	<0.001
Low birth weight (yes)	54 (7.3%)	39 (3.1%)	<0.001
Preterm birth (yes)	101 (13.7%)	52 (4.1%)	<0.001
Children sex (boy)	429 (58.3%)	664 (52.3%)	0.01
Children sex (girl)	307 (41.7%)	606 (47.7%)	0.01
Cola (yes)
Pre-pregnancy	439 (59.5%)	–	–
1st trimester	47 (7.7%)	553 (43.5%)	<0.001
2nd trimester	81 (34.5%)	154 (65.5%)	0.208
3rd trimester	73 (40.3%)	108 (59.7%)	0.004
Total food energy (Kcal)
Pre-pregnancy	952.4 (577.0)	–	–
1st trimester	916.7 (612.6)	552.2 (183.5)	<0.001
2nd trimester	1,054.1 (525.0)	560.3 (153.1)	<0.001
3rd trimester	999.8 (523.6)	507.5 (163.7)	<0.001
Alcohol (yes)	1 (0.2%)	295 (23.2%)	<0.001
Tea (yes)	20 (3.3%)	464 (36.5%)	<0.001
Coffee (yes)	2 (0.3%)	391 (30.8%)	<0.001
Functional Beverages (yes)	7 (1.1%)	158 (12.4%)	<0.001
Multiparity	67 (9.1%)	397 (31.3%)	<0.001
Exercise (day/week)
Rarely	492 (80.4%)	665 (52.4%)	<0.001
<3 times/week	77 (12.6%)	372 (29.3%)
≥3 times/week	43 (7.0%)	233 (18.4%)
Reasons of infertility
Female	382 (53.1%)	–	–
Male	173 (24.1%)	–	–
Both	122 (17.0%)	–
Unclear	42 (5.8%)	–

Participant characteristics of ART and SC cohorts were mainly from the 1st trimester for comparison except for other marked, and the results of comparison were indicated by p value. – refers no participant observed in the term. SC, spontaneously conceived. ART, assisted reproductive technology.

Table 2. The association of cola intake with preterm birth and low birth weight in the spontaneously conceived women.

	RR (95%CI)
	1st trimester	2nd trimester	3rd trimester	At least one trimester in all three trimesters
Preterm birth
Uni-model	n = 1880	n = 1825	n = 1730	n = 1896
Cola	0.88 (0.62 to 1.26)	1.62 (1.06 to 2.47)*	2.00 (1.24 to 3.21)*	0.94 (0.68 to 1.31)
Multi-model 1	n = 1875	n = 1820	n = 1727	n = 1891
Cola	1.00 (0.70 to1.44)	1.54 (1.01 to 2.35)*	1.74 (1.09 to 2.78)*	1.02 (0.73 to 1.44)
Low birth weight
Uni-model	n = 1880	n = 1825	n = 1730	n = 1896
Cola	0.99 (0.64 to 1.55)	0.87 (0.44 to 1.73)	1.49 (0.75 to 2.97)	0.76 (0.49 to 1.17)
Multi-model 1	n = 1875	n = 1820	n = 1727	n = 1891
Cola	1.14 (0.72 to 1.81)	0.86 (0.44 to 1.70)	1.39 (0.69 to 2.81)	0.83 (0.53 to 1.29)

At least one trimester in all three trimesters refers to any cola intake was defined as at least one cola intake in at least one of the three trimesters, and no cola intake was defined as no cola intake in all three trimesters for participants who presented all three visits. RR, the ratio of probability of an outcome in cola exposure group to non-cola exposure group. CI, confidence interval.*, p value for the RR < 0.05. Multi-model 1 was adjusted for age, BMI at baseline, multiparity, gender of neonate, alcohol, tea, coffee, functional beverage, total intake energy, exercise frequency and the reasons of infertility. Multi-model 2 was further adjusted for cola intake pre-pregnancy above the multi-model 1.

Table 3. The association of cola intake with preterm birth and low birth weight in the assisted reproductive technology women.

	RR (95%CI)
	Pre-pregnancy	1st trimester	2nd trimester	3rd trimester	At least one trimester in all three trimesters
Preterm birth
Uni-model	n = 736	n = 610	n = 563	n = 533	n = 626
Cola	1.29 (0.93 to 1.80)	2.13 (1.28 to 3.55)*	1.67 (1.01 to 2.75)*	2.03 (1.17 to 3.52)*	1.60 (1.06 to 2.43)*
Multi-model 1	n = 736	n = 610	n = 563	n = 533	n = 626
Cola	1.20 (0.81 to 1.78)	2.34 (1.41 to 3.88)*	1.70 (1.02 to 2.85)*	1.80 (1.01 to 3.21)*	1.60 (1.04 to 2.46)*
Multi-model 2	–	n = 610	n = 563	n = 533	n = 507
Cola	–	2.10 (1.23 to 3.60)*	1.65 (0.97 to 2.83)	1.81 (1.05 to 3.12)*	1.57 (1.00 to 2.44)*
Low birth weight
Uni-model	n = 736	n = 610	n = 563	n = 533	n = 629
Cola	0.99 (0.59 to 1.67)	2.52 (1.25 to 5.09)*	0.67 (0.25 to 1.84)	1.67 (0.70 to 3.96)	1.24 (0.64 to 2.40)
Multi-model 1	n = 736	n = 610	n = 563	n = 533	n = 507
Cola	1.04 (0.59 to 1.83)	2.58 (1.29 to 5.16)*	0.70 (0.27 to 1.78)	1.29 (0.55 to 3.06)	1.22 (0.63 to 2.36)
Multi-model 2	–	n = 610	n = 563	n = 533	n = 507
Cola	–	2.72 (1.33 to 5.53)*	0.65 (0.23 to 1.82)	1.56 (0.65 to 3.72)	1.26 (0.64 to 2.49)

At least one trimester in all three trimesters refers to any cola intake was defined as at least one cola intake in at least one of the three trimesters, and no cola intake was defined as no cola intake in all three trimesters for participants who presented all three visits. RR, the ratio of probability of an outcome in cola exposure group to non-cola exposure group. CI, confidence interval.*, p value for the RR < 0.05. Multi-model 1 was adjusted for age, BMI at baseline, multiparity, gender of neonate, alcohol, tea, coffee, functional beverage, total intake energy, exercise frequency and the reasons of infertility. Multi-model 2 was further adjusted for cola intake pre-pregnancy above the multi-model 1.

Table 5. The association between consistency of cola intake during pregnancy and preterm birth/low birth weight in the ART and SC cohort.

	ART		SC
	RR (95%CI)	p	RR (95%CI)	p
Preterm birth
Uni-model	n = 507		n = 1191
Frequency of cola intake in three trimesters
None of trimesters	Reference		Reference
One trimester	1.61 (0.84 to 3.07)	0.15	1.17 (0.61 to 2.22)	0.64
Two trimesters	2.87 (1.47 to 5.60)	0.002	1.44 (0.50 to 4.19)	0.50
Three trimesters	1.79 (0.49 to 6.60)	0.38	4.42 (1.40 to 13.98)	0.01
p for trend	1.45 (1.13 to 1.86)	0.003	1.41 (0.94 to 2.12)	0.10
Multi-model 1	n = 507		n = 1188
Frequency of cola intake in three trimesters
None of trimesters	Reference		Reference
One trimester	1.50 (0.77 to 2.91)	0.24	0.99 (0.49 to 1.97)	0.97
Two trimesters	2.65 (1.36 to 5.17)	0.004	1.13 (0.39 to 3.24)	0.82
Three trimesters	1.72 (0.60 to 4.90)	0.31	3.45 (1.08 to 11.00)	0.04
p for trend	1.41 (1.12 to 1.77)	0.003	1.27 (0.82 to 1.97)	0.28
Low birth weight
Uni-model	n = 507		n = 1191
Frequency of cola intake during three trimesters
None of trimesters	Reference		Reference
One trimester	0.89 (0.27 to 2.92)	0.85	0.97 (0.46 to 2.04)	0.93
Two trimesters	3.32 (1.34 to 8.22)	0.01	1.31 (0.38 to 4.48)	0.67
Three trimesters	*	*	3.58 (0.87 to 14.80)	0.08
p for trend	1.28 (0.85 to 1.92)	0.23	1.28 (0.77 to 2.12)	0.34
Multi-model 1	n = 507		n = 1188
Frequency of cola intake during three trimesters
None of trimesters	Reference		Reference
One trimester	0.81 (0.24 to 2.68)	0.73	0.91 (0.42 to 2.00)	0.82
Two trimesters	3.18 (1.27 to 7.95)	0.01	1.22 (0.34 to 4.32)	0.76
Three trimesters	*	*	3.54 (0.89 to 14.02)	0.07
p for trend	1.25 (0.83 to 1.88)	0.28	1.26 (0.75 to 2.12)	0.39

ART, assisted reproductive technology. SC, spontaneously conceived. The consistency of cola intake in three trimesters refers how many trimesters of exposure cola in all three trimesters. RR, the ratio of probability of an outcome in cola exposure group to non-cola exposure group. CI, confidence interval. p value is for the RR. Multi-model 1 was adjusted for age, BMI at baseline, multi-parity, gender of neonate, alcohol, tea, coffee, functional beverage, total intake energy, exercise frequency and the reasons of infertility. *, only 12 ART women were exposed to cola in all three trimesters, and the birth weight of their neonates were heavier than 2500 g.

Table 4. The association of cola intake with preterm birth and low birth weight in the spontaneous conceived women.

	RR (95%CI)
	1st trimester	2nd trimester	3rd trimester	At least one trimester in all three trimesters
Preterm birth
Uni-model	n = 1270	n = 1262	n = 1197	n = 1270
Cola	1.40 (0.82 to 2.39)	1.31 (0.63 to 2.73)	1.33 (0.53 to 3.30)	1.19 (0.70 go 2.05)
Multi-model 1	n = 1265	n = 1257	n = 1194	n = 1265
Cola	1.33 (0.73 to 2.42)	1.32 (0.64 to 2.72)	1.37 (0.55 to 3.41)	1.10 (0.62 to 1.98)
Low birth weight
Uni-model	n = 1270	n = 1262	n = 1197	n = 1270
Cola	1.23 (0.66 to 2.29)	1.06 (0.42 to 2.67)	1.04 (0.32 to 3.37)	0.92 (0.50 to 1.71)
Multi-model 1	n = 1265	n = 1257	n = 1194	n = 1265
Cola	1.36 (0.69 to 2.66)	1.18 (0.49 to 2.81)	1.15 (0.32 to 4.15)	0.97 (0.50 to 1.86)

RR, the ratio of probability of an outcome in cola exposure group to non-cola exposure group. CI, confidence interval. p value is for the RR. Multi-model 1 was adjusted for age, BMI at baseline, multi-parity, gender of neonate, alcohol, tea, coffee, functional beverage, total intake energy, exercise frequency and the reasons of infertility.

Availability of data and materials

The datasets generated and/or analysed during the current study are not publicly available due to the funding requirement but are available from the corresponding author on reasonable request.