Association between length of gestation and cervical DNA methylation of PTGER2 and LINE 1-HS

Figures & data

Table 1. Cervical DNA methylation of the prostaglandin E receptor 2 (PTGER2) and long interspersed nuclear element-1 (LINE 1-HS) ELEMENT birth cohort, Mexico City

				PTGER2 (n = 77)				LINE 1-HS (n = 78)
Participant Characteristics (n = 80)*	n	%		Mean % 5mC	SD	Chi-square P value		Mean % 5mC		SD	Chi-square P value
Maternal age (years)						0.28					0.59
<20	6	7.5		35.7	10.5				68.1	3.1
20 – <35	64	80.0		31.2	15.9				69.1	4.3
≥35	10	12.5		40.3	18.3				67.6	4.7	0.585
Parity						0.46					0.17
Nulliparous	38	47.5		34.0	16.3				68.1	3.9
Multiparous	42	52.5		31.3	15.7				69.4	4.5
Smoked before pregnancy						0.04					0.22
Yes	48	60.0		29.4	16.0				69.3	4.3
No	32	40.0		37.1	15.0				68.1	4.2
Smoke exposure in the home						0.40					0.28
Yes	57	71.3		30.1	15.4				68.0	4.3
No	23	28.7		33.5	16.2				69.1	4.3
Education (years)						0.92					0.21
<12	22	27.5		32.8	16.3				69.8	4.1
≥12	58	72.5		32.4	15.9				68.4	4.4
Pre-pregnancy BMI (kg/m^2)						0.12					0.17
<25	45	56.3		30.8	15.9				69.1	4.3
25 – <30	23	27.7		31.5	15.3				69.3	4.1
≥30	12	15.0		41.6	15.6				66.7	4.5
Pap smear inflammation						<0.001					<0.001
No	45	59.2		38.1	13.8				67.2	3.5
Yes	31	40.8		24.5	14.2				71.1	4.2
Gestational Age groups						0.79					0.50
<37	7	9.2		31.0	15.9				70.4	4.6
37–38	33	43.4		32.0	15.7				68.8	4.4
≥39	36	47.4		34.3	15.9				68.4	4.1
Method of Delivery						0.13					0.79
Vaginal	37	48.7		30.1	14.8				68.9	4.3
Cesarean Section	39	51.3		35.6	16.0				68.6	4.2
Premature rupture of membranes						0.06					0.019
Yes	13	17.1		25.1	15.1				70.2	4.5
No	63	82.9		34.5	15.4				68.5	4.1

* 80 mothers agreed to participate, but 4 mothers dropped out before delivery. 76/80 Pap Smear results, 77/80 successful assays for PTGER2 and 78/80 for LINE 1-HS.

Table 2. Associations of maternal characteristics and cervical DNA methylation, ELEMENT birth cohort, Mexico City

	PTGER2 β^ in % 5mC (95% CI)			LINE 1-HS β^ in % 5mC (95% CI)
Maternal characteristics
	Model 1	Model 2		Model 1	Model 2
Maternal age (years)
< 20	5.4 (-8.2, 19.0)	3.2 (-9.2, 15.6)		-1.6 (-5.3, 2.1)	-0.9 (-4.1, 2.3)
20- < 35	ref.	ref.		ref.	ref.
≥ 35	3.8 (-9.1, 16.7)	6.5 (-5.3, 18.3)		-0.7 (-3.8, 2.4)	-2.1 (-4.8, 0.4)
Maternal pre-pregnancy BMI per kg/m^2	0.7 (-0.2, 1.6)	0.6 (-0.2, 1.5)		-0.2 (-0.5, 0.0)	-0.2 (-0.4, 0.0)
Primiparous (vs. multiparous)	-4.1 (-11.8, 3.5)	-6.0 (-13.0, 1.0)		1.7 (-0.3, 3.7)	2.3 (0.5, 4.1)
Maternal Education (> = 12 y vs. less)	-3.4 (-11.6, 4.9)	-5.9 (-13.6, 1.7)		-0.5 (-2.7, 1.8)	0.4 (-1.6, 2.3)
Smoking exposure within the home (vs. not)	-2.2 (-10.3, 6.0)	0.8 (-6.8, 8.4)		-1.6 (-3.7, 0.9)	-2.5 (-4.4, -0.6)
Smoking prior to pregnancy (vs. never)	-6.8 (-14.6, 1.1)	-4.3 (-11.5, 3.0)		1.6 (-0.5, 3.7)	0.8 (-1.1, 2.6)
Maternal second trimester blood lead per μg/dl	0.5 (-1.6, 2.6)	0.3 (-1.6, 2.2)		0.0 (-0.6, 0.5)	0.1 (-0.4, 0.5)
Pap smear inflammation (vs. not)		-13.5 (-20.6, -6.4)			4.5 (2.7, 6.3)

PTGER2 prostaglandin E receptor 2 (subtype EP2); LINE 1-HS long interspersed nuclear element-1 Homo sapiens-specific. PTGER2 models include 73 participants; LINE 1-HS models include 75 participants. ^β coefficients obtained from linear regression models inclusive of all variables listed.

Figure 1. Cervical prostaglandin E receptor 2 (subtype EP2) (PTGER2) DNA methylation and gestational age (days), ELEMENT birth cohort, Mexico City (n = 73).

Figure 2. Cervical long interspersed nuclear element-1 Homo sapiens specific (LINE 1-HS) DNA methylation and gestational age (days), ELEMENT birth cohort, Mexico City (n = 74).

Figure 3. Gestational Age Differences per interquartile range of cervical DNA methylation of PTGER2 and LINE 1-HS, ELEMENT birth cohort, Mexico City. Model 1: Unadjusted Model 2: Adjusted for maternal age Model 3: Model 2 additionally adjusted for Pap smear inflammation Abbreviations: PTGER2 prostaglandin E receptor 2 (subtype EP2); LINE 1-HS long interspersed nuclear element-1 Homo sapiens-specific. Footnote: n = 69 for PTGER2 models and n = 71 for LINE 1-HS models; error bars indicate 95% confidence intervals.