Association Between Triglyceride Glucose Index and Infertility in Reproductive-Aged Women: A Cross-Sectional Study

Figures & data

Figure 1 Flow chart of the inclusion and exclusion of study participants.

Table 1 Baseline Characteristics of Participants

Characteristic	Total	Control	Infertility	P-value
	N=1556	N=1387	N=169
Age, (years)	31.40 ± 8.07	30.92 ± 8.03	34.88 ± 7.51	<0.001
Poverty income ratio (PIR)	2.56 ± 1.64	2.55 ± 1.64	2.69 ± 1.66	0.294
Fasting Glucose (mg/dl)	98.33 ± 22.05	97.77 ± 20.09	102.40 ± 32.63	0.007
Total Cholesterol (mg/dl)	179.37 ± 35.88	179.25 ± 35.73	180.25 ± 36.97	0.718
HDL Cholesterol (mg/dl)	57.76 ± 15.97	58.27 ± 15.99	54.04 ± 15.35	<0.001
LDL cholesterol (mg/dl)	103.47 ± 30.50	103.04 ± 30.37	106.65 ± 31.27	0.123
Triglyceride (mg/dl)	91.30 ± 62.01	90.21 ± 59.94	99.22 ± 74.88	0.061
HbA1c (%)	5.34 ± 0.67	5.31 ± 0.63	5.51 ± 0.94	<0.001
TyG	8.22 ± 0.63	8.21 ± 0.63	8.34 ± 0.63	0.005
Race, (%)				0.486
Mexican American	11.93	12.26	9.56
Other Hispanic	7.89	8.03	6.93
Non-Hispanic white	55.90	55.07	61.89
Non-Hispanic black	13.16	13.26	12.41
Other Races	11.12	11.38	9.21
Education level (%)				0.253
Less than high school	12.04	11.82	13.57
High school	20.72	21.38	16.27
Above high school	67.23	66.80	70.17
Marital status				<0.001
Married or living with partner	60.48	57.47	80.92
Living alone	39.52	42.53	19.08
BMI (kg/m^2)				<0.001
<25	36.57	38.18	24.95
≥25	63.43	61.82	75.05
Smoking status (%)				0.027
Yes	31.61	30.64	38.59
No	68.39	69.36	61.41
Alcohol drinking status (%)				0.007
Yes	7.70	6.92	12.80
No	92.30	93.08	87.20
Hypertension (%)				<0.001
Yes	14.10	12.55	25.35
No	85.90	87.45	74.65
Diabetes (%)				<0.001
Yes	4.78	3.91	11.03
No	95.22	96.09	88.97
Had regular periods in past 12 months (%)				<0.001
Yes	89.33	90.33	82.14
No	10.67	9.67	17.86
Ever treated for a pelvic infection/PID (%)				0.003
Yes	4.25	3.69	8.28
No	95.75	96.31	91.72
Ever taken birth control pills (%)				0.140
Yes	73.18	72.56	77.65
No	26.82	27.44	22.35

Table 2 Associations Between TyG Index and the Risk of Infertility

TyG Index	Infertility [OR (95% CI)]
Crude model (model 1)
Continuous	1.41 (1.12, 1.79)
Categories
Quartile 1	Reference
Quartile 2	1.51 (0.99, 2.29)
Quartile 3	1.65 (1.10, 2.49)
Minimally adjusted model (model 2)
Continuous	1.45 (1.14, 1.85)
Categories
Quartile 1	Reference
Quartile 2	1.52 (1.00, 2.32)
Quartile 3	1.72 (1.13, 2.63)
Fully adjusted model (model 3)
Continuous	1.51 (1.14, 2.00)
Categories
Quartile 1	Reference
Quartile 2	1.78 (1.12, 2.83)
Quartile 3	1.72 (1.05, 2.84)

Notes: In sensitivity analysis, the TyG index was converted from a continuous variable to a categorical variable (tertiles). Model 1, No covariates were adjusted; Model 2, Adjusted for age and race; Model 3, Adjusted for age, ratio of family income to poverty, race, education level, marital status, smoked at least 100 cigarettes, had at least 12 alcohol drinks/1 year, ever treated for a pelvic infection/PID, ever taken birth control pills, had regular periods in past 12 months.

Abbreviations: 95% CI, 95% Confidence Interval; OR, Odds Ratio.

Figure 2 Smoothing curve fitting of TyG index and infertility.

Table 3 Subgroups Analyses of the effect of TyG Index on Infertility

Subgroup	Infertility [OR (95% CI)]	P for Interaction
Age		0.056
<35	0.96 (0.62, 1.47)
≥35	1.81 (1.10, 2.99)
Marital status		0.843
Married or living with partner	1.04 (0.74, 1.46)
Living alone	1.11 (0.65, 1.90)
Education level		0.633
Less than high school	1.19 (0.56, 2.53)
High school	1.08 (0.51, 2.28)
Above high school	0.98 (0.68, 1.41)
BMI		0.837
<25	1.17 (0.57, 2.40)
≥25	1.08 (0.78, 1.49)
Smoking status		0.820
Yes	1.27 (0.77, 2.10)
No	1.18 (0.78, 1.77)
Alcohol drinking status		0.765
Yes	0.98 (0.32, 3.04)
No	1.18 (0.84, 1.65)
Diabetes		0.333
Yes	1.75 (0.68, 4.54)
No	1.07 (0.78, 1.48)
Hypertension		0.210
Yes	0.79 (0.46, 1.36)
No	1.19 (0.84, 1.68)
Had regular periods in past 12 months		0.113
Yes	1.14(0.82,1.59)
No	3.07(0.91,10.39)
Ever treated for a pelvic infection/PID		0.110
Yes	3.04(0.85,10.88)
No	1.09(0.79,1.51)

Figure 3 ROC curve of the TyG index used to diagnose infertility.

Data Sharing Statement

Publicly available datasets were analyzed in this study. This data can be found here: https://wwwn.cdc.gov/nchs/nhanes.