J Clin Gynecol Obstet

Journal of Clinical Gynecology and Obstetrics, ISSN 1927-1271 print, 1927-128X online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Gynecol Obstet and Elmer Press Inc

Journal website https://jcgo.elmerpub.com

Original Article

Volume 000, Number 000, May 2025, pages 000-000

A Parity-Based Analysis of Women of Advanced Maternal Age and Delivery

**Table 1.** Demographic and Clinical Characteristics of Women of AMA and Their Younger Counterparts (in Their Twenties)
Nulliparous women	Young, N = 1,432	AMA, N = 514	P
Age (years)	26.5 ± 2.3	37.0 ± 2.0
Age ≥ 40, N (%), max.	0 (0), 29	67 (13.0), 45
Maternal height (cm)	158.2 ± 5.1	158.6 ± 5.4	0.096^a
Prepregnancy body weight (kg)	50.3 ± 6.5	52.0 ± 6.9	< 0.001^a
Body mass index (kg/m²)	20.1 ± 2.3	20.7 ± 2.5	< 0.001^a
Gestational age (days)	277.3 ± 6.7	277.7 ± 6.7	0.21^a
Gestational weight gain (kg)	10.9 ± 3.6	10.5 ± 3.4	0.031^a
Neonatal weight (g)	2,997 ± 334	3,020 ± 364	0.19^a
Neonatal head circumference (cm)	33.2 ± 1.2	33.3 ± 1.3	0.26^a
Pregnancy by ART, N (%)	11 (0.8)	69 (13.4)	< 0.001^b
Induction of labor, N (%)	184 (12.8)	140 (27.2)	< 0.001^b
Umbilical artery pH	7.30 ± 0.07	7.30 ± 0.07	0.24^a
Umbilical artery base excess	-3.7 ± 3.1	-4.0 ± 3.3	0.057^a
Apgar score at 5 min ≤ 7, N (%)	4 (0.3)	5 (1.0)	0.11^b
Blood loss (g)	407 ± 294	457 ± 312	0.002^a
Epidural, N (%)	61 (4.3)	44 (8.6)	< 0.001^b
^aUnpaired t-test. ^bFisher’s exact test. AMA: advanced maternal age; ART: assisted reproductive technology.
Age (years)	26.9 ± 2.23	37.2 ± 2.0
Age ≥ 40, N (%), max.	0 (0), 29	150 (13.4), 45
Parity	2.2 ± 0.4	2.4 ± 0.7	< 0.001^a
Maternal height (cm)	158.0 ± 5.1	158.5 ± 5.1	0.034^a
Prepregnancy body weight (kg)	50.9 ± 7.5	52.5 ± 7.2	< 0.001^a
Body mass index (kg/m²)	20.4 ± 2.9	20.9 ± 2.8	0.002^a
Gestational age (days)	274.7 ± 6.1	275.0 ± 6.5	0.28^a
Gestational weight gain (kg)	10.6 ± 3.3	9.7 ± 3.2	< 0.001^a
Neonatal weight (g)	3,051 ± 326	3,103 ± 368	0.0013^a
Neonatal head circumference (cm)	33.4±1.1	33.5 ± 1.2	0.0025^a
Pregnancy by ART, N (%)	1 (0.1)	64 (5.7)	< 0.001^b
Induction of labor, N (%)	106 (12.5)	214 (19.2)	< 0.001^b
Umbilical artery pH	7.34 ± 0.07	7.32 ± 0.07	< 0.001^a
Umbilical artery base excess	-1.3 ± 2.8	-2.0 ± 2.9	< 0.001^a
Apgar Score at 5 min ≤ 7, N (%)	1 (0.1)	4 (0.4)	0.55^b
Blood loss (g)	333 ± 249	349 ± 259	0.16^a
Epidural, N (%)	36 (4.3)	78 (7.2)	0.011^b

Table 1. Demographic and Clinical Characteristics of Women of AMA and Their Younger Counterparts (in Their Twenties)

Nulliparous women

Young, N = 1,432

AMA, N = 514

Age (years)

26.5 ± 2.3

37.0 ± 2.0

Age ≥ 40, N (%), max.

0 (0), 29

67 (13.0), 45

Maternal height (cm)

158.2 ± 5.1

158.6 ± 5.4

0.096^a

Prepregnancy body weight (kg)

50.3 ± 6.5

52.0 ± 6.9

< 0.001^a

Body mass index (kg/m²)

20.1 ± 2.3

20.7 ± 2.5

< 0.001^a

Gestational age (days)

277.3 ± 6.7

277.7 ± 6.7

0.21^a

Gestational weight gain (kg)

10.9 ± 3.6

10.5 ± 3.4

0.031^a

Neonatal weight (g)

2,997 ± 334

3,020 ± 364

0.19^a

Neonatal head circumference (cm)

33.2 ± 1.2

33.3 ± 1.3

0.26^a

Pregnancy by ART, N (%)

11 (0.8)

69 (13.4)

< 0.001^b

Induction of labor, N (%)

184 (12.8)

140 (27.2)

< 0.001^b

Umbilical artery pH

7.30 ± 0.07

0.24^a

Umbilical artery base excess

-3.7 ± 3.1

-4.0 ± 3.3

0.057^a

Apgar score at 5 min ≤ 7, N (%)

4 (0.3)

5 (1.0)

0.11^b

Blood loss (g)

407 ± 294

457 ± 312

0.002^a

Epidural, N (%)

61 (4.3)

44 (8.6)

< 0.001^b

Multiparous women

Young, N = 845

AMA, N = 1,116

^aUnpaired t-test. ^bFisher’s exact test. AMA: advanced maternal age; ART: assisted reproductive technology.

Age (years)

26.9 ± 2.23

37.2 ± 2.0

Age ≥ 40, N (%), max.

0 (0), 29

150 (13.4), 45

Parity

2.2 ± 0.4

2.4 ± 0.7

< 0.001^a

Maternal height (cm)

158.0 ± 5.1

158.5 ± 5.1

0.034^a

Prepregnancy body weight (kg)

50.9 ± 7.5

52.5 ± 7.2

< 0.001^a

Body mass index (kg/m²)

20.4 ± 2.9

20.9 ± 2.8

0.002^a

Gestational age (days)

274.7 ± 6.1

275.0 ± 6.5

0.28^a

Gestational weight gain (kg)

10.6 ± 3.3

9.7 ± 3.2

< 0.001^a

Neonatal weight (g)

3,051 ± 326

3,103 ± 368

0.0013^a

Neonatal head circumference (cm)

33.4±1.1

33.5 ± 1.2

0.0025^a

Pregnancy by ART, N (%)

1 (0.1)

64 (5.7)

< 0.001^b

Induction of labor, N (%)

106 (12.5)

214 (19.2)

< 0.001^b

Umbilical artery pH

7.34 ± 0.07

7.32 ± 0.07

< 0.001^a

Umbilical artery base excess

-1.3 ± 2.8

-2.0 ± 2.9

< 0.001^a

Apgar Score at 5 min ≤ 7, N (%)

1 (0.1)

4 (0.4)

0.55^b

Blood loss (g)

333 ± 249

349 ± 259

0.16^a

Epidural, N (%)

36 (4.3)

78 (7.2)

0.011^b

**Table 2.** Mode of Delivery
Nulliparous women	Young, N = 1,432	AMA, N = 514	P^a
Normal vaginal	1,292 (90.2)	395 (76.8)	< 0.001
Vacuum extraction	124 (9.4)	82 (16.0)	< 0.001
Cesarean section	16 (1.1)	37 (7.2)	< 0.001
^aResidual analysis. Young: in their twenties; AMA: advanced maternal age, ≥ 35.
Normal vaginal	832 (98.5)	1,066 (95.5)	< 0.001
Vacuum extraction	13 (1.5)	48 (4.3)	< 0.001
Cesarean section	0 (0.0)	2 (0.2)	0.218

Table 2. Mode of Delivery

Nulliparous women

Young, N = 1,432

AMA, N = 514

P^a

Normal vaginal

1,292 (90.2)

395 (76.8)

< 0.001

Vacuum extraction

124 (9.4)

82 (16.0)

< 0.001

Cesarean section

16 (1.1)

37 (7.2)

< 0.001

Multiparous women

Young, N = 845

AMA, N = 1,116

P^a

^aResidual analysis. Young: in their twenties; AMA: advanced maternal age, ≥ 35.

Normal vaginal

832 (98.5)

1,066 (95.5)

< 0.001

Vacuum extraction

13 (1.5)

48 (4.3)

< 0.001

Cesarean section

0 (0.0)

2 (0.2)

0.218

**Table 3.** Indication for Cesarean Sections
	Young	AMA
CPD: cephalopelvic disproportion; FTP: failure to progress; NRFS: non-reassuring fetal status; Young: in their twenties; AMA: advanced maternal age, ≥ 35.
Nulliparous women
CPD/FTP	12	34
NRFS	4	2
Forelying umbilical cord	0	1
Multiparous women
CPD/FTP	0	1
Face presentation	0	1

Table 3. Indication for Cesarean Sections

Young

AMA

CPD: cephalopelvic disproportion; FTP: failure to progress; NRFS: non-reassuring fetal status; Young: in their twenties; AMA: advanced maternal age, ≥ 35.

Nulliparous women

CPD/FTP

NRFS

Forelying umbilical cord

Multiparous women

CPD/FTP

Face presentation

**Table 4.** Duration of Labor
	Young	AMA	P^a
Data are presented as median (10 percentile, 90 percentile) (min). ^aMann-Whitney U test. Young: in their twenties; AMA: advanced maternal age, ≥ 35.
Nulliparous women
Duration of labor, first stage
Total	570 (216 - 1,340)	527 (210 - 1,290)	0.16
Without epidural	560 (211 - 1,266)	510 (202 - 1,200)	0.069
Duration of labor, second stage
Total	50 (18 - 145)	77 (25 - 253)	< 0.001
Without epidural	49 (18 - 129)	75 (23 - 177)	< 0.001
Multiparous women
Duration of labor, first stage
Total	265 (105 - 572)	245 (95 - 560)	0.052
Without epidural	265 (110 - 571)	245 (95 - 580)	0.035
Duration of labor, second stage
Total	11 (4 - 31)	14 (4 - 43)	< 0.001
Without epidural	11 (4 - 30)	13 (4 - 42)	< 0.001

Table 4. Duration of Labor

Young

AMA

P^a

Data are presented as median (10 percentile, 90 percentile) (min). ^aMann-Whitney U test. Young: in their twenties; AMA: advanced maternal age, ≥ 35.

Nulliparous women

Duration of labor, first stage

Total

570 (216 - 1,340)

527 (210 - 1,290)

0.16

Without epidural

560 (211 - 1,266)

510 (202 - 1,200)

0.069

Duration of labor, second stage

Total

50 (18 - 145)

77 (25 - 253)

< 0.001

Without epidural

49 (18 - 129)

75 (23 - 177)

< 0.001

Multiparous women

Duration of labor, first stage

Total

265 (105 - 572)

245 (95 - 560)

0.052

Without epidural

265 (110 - 571)

245 (95 - 580)

0.035

Duration of labor, second stage

Total

11 (4 - 31)

14 (4 - 43)

< 0.001

Without epidural

11 (4 - 30)

13 (4 - 42)

< 0.001

**Table 5.** Frequency of Prolonged Labor
	Young	AMA	P^a	OR (95% CI)
^aFisher’s exact test. ^b> 2 h without epidural, > 3 h with epidural. ^c> 1 h without epidural, > 2 h with epidural. Young: in their twenties; AMA: advanced maternal age, ≥ 35; CI: confidence interval; OR: odds ratio.
First stage of labor
Nulliparous women, > 20 h	13.6% (192/1,416)	12.2% (58/477)	0.48	0.88 (0.65 - 1.21)
Multiparous women, > 14 h	2.6% (22/845)	3.0% (33/1,109)	0.68	1.15 (0.68 - 1.97)
Second stage of labor
Nulliparous women^b	14.8% (210/1,416)	27.7% (132/477)	< 0.001	2.20 (1.72 - 2.82)
Multiparous women^c	2.1% (18/844)	5.2% (57/1,111)	< 0.001	2.48 (1.46 - 4.22)

Table 5. Frequency of Prolonged Labor

Young

AMA

P^a

OR (95% CI)

^aFisher’s exact test. ^b> 2 h without epidural, > 3 h with epidural. ^c> 1 h without epidural, > 2 h with epidural. Young: in their twenties; AMA: advanced maternal age, ≥ 35; CI: confidence interval; OR: odds ratio.

First stage of labor

Nulliparous women, > 20 h

13.6% (192/1,416)

12.2% (58/477)

0.48

0.88 (0.65 - 1.21)

Multiparous women, > 14 h

2.6% (22/845)

3.0% (33/1,109)

0.68

1.15 (0.68 - 1.97)

Second stage of labor

Nulliparous women^b

14.8% (210/1,416)

27.7% (132/477)

< 0.001

2.20 (1.72 - 2.82)

Multiparous women^c

2.1% (18/844)

5.2% (57/1,111)

< 0.001

2.48 (1.46 - 4.22)