Association of COVID-19 vaccination before conception with maternal liver function during early pregnancy: a cohort study of 7745 Chinese pregnant women

Figures & data

Figure 1. The flow chart of participants enrolment. A total of 7745 pregnant women were included in the final analysis. Among the 7745 participating pregnant women, 3832 (49.5%) received at least two doses of an inactivated vaccine.

Table 1. General characteristics of the participating pregnant women.

Characteristics ^a	Total (N = 7745)	Vaccination		p-value ^b
		Yes (N = 3832)	No (N = 3913)
Maternal age
< 35	6521 (84.2%)	3251 (84.8%)	3270 (83.6%)	0.125
≥ 35	1224 (15.8%)	581 (15.2%)	643 (16.4%)
Parity
Nulliparous	6197 (80.0%)	2804 (73.2%)	3393 (86.7%)	< 0.01**
Multiparous	1548 (20.0%)	1028 (26.8%)	520 (13.3%)
Pregnancy BMI
< 18.5	959 (12.4%)	487 (12.7%)	472 (12.1%)	0.176
18.5-24.9	5939 (76.7%)	2950 (77.0%)	2989 (76.4%)
≥ 25	847 (10.9%)	395 (10.3%)	452 (11.6%)
Mode of conception
The use of ART	247 (3.2%)	40 (1.0%)	207 (5.3%)	< 0.01**
Natural Conception	7498 (96.8%)	3792 (99.0%)	3706 (94.7%)
Abortion history
Yes	1874 (24.2%)	780 (20.4%)	1094 (28.0%)	< 0.01**
No	5871 (75.8)	3052 (79.6%)	2819 (72.0%)

^a Values are shown as percent (%).

^b p-values were calculated by chi-square test.

** p < 0.01.

Table 2. Distribution of serum ALT, AST, TBA and TBIL in early pregnancy.

Characteristics ^a	Total (N = 7745)	Vaccination		p-value ^b
		Yes (N = 3832)	No (N = 3913)
ALT (U/L)	19.13 ± 18.54	18.59 ± 17.20	19.66 ± 19.75	0.011 *
AST (U/L)	19.61 ± 8.39	19.37 ± 8.02	19.84 ± 8.72	0.012 *
TBA (μmol/L)	2.26 ± 2.27	2.33 ± 2.43	2.20 ± 2.10	0.022 *
TBIL (μmol/L)	9.27 ± 3.49	9.42 ± 3.61	9.13 ± 3.36	< 0.001**

^a Values are shown as mean (± SD).

^b p-values were calculated by student’s t-test.

* p < 0.05, ** p < 0.01.

Table 3. Effect estimates (95% CI) of serum ALT, AST, TBA and TBIL levels associated with COVID-19 vaccination before conception.

	Unvaccinated	Vaccinated	Time interval from vaccination to pregnancy
			≤ 3 months	> 3 months
ALT	0 (Reference)	−0.16 (−1.01, 0.69)	−0.14 (−1.22, 0.94)	−0.18 (−1.18, 0.82)
AST	0 (Reference)	−0.04 (−0.43, 0.34)	0.14 (−0.35, 0.63)	−0.19 (−0.64, 0.26)
TBA	0 (Reference)	0.07 (−0.04, 0.18)	0.17 (0.04, 0.31) *	−0.01 (0.13, 0.12)
TBIL	0 (Reference)	0.05 (−0.11, 0.21)	0.05 (−0.16, 0.25)	0.05 (−0.14, 0.24)

^a Adjusted for GA at the time of liver function assessment, maternal age, parity, model of conception, abortion history and pre-pregnancy body mass index.

* p < 0.05.

Table 4. Relative risk of maternal hyperbileacidemia associated with COVID-19 vaccination before pregnancy.

	Model, RR (95% CI)
	Crude model	Adjusted model ^a
Unvaccinated	1.00 (Reference)	1.00 (Reference)
Vaccinated	1.79 (1.06, 3.02) *	1.62 (0.95, 2.78)
Time interval
≤ 3 months	2.37 (1.31, 4.26) **	2.13 (1.17, 3.87) *
> 3 months	1.36 (0.73, 2.56)	1.22 (0.64, 2.34)

^a Adjusted for GA at the time of liver function assessment, maternal age, maternal parity, mode of conception, abortion history and pre-pregnancy body mass index.

* p < 0.05, ** p < 0.01.