Comparative study of pregnancy risks in different maternal age groups

Amala Sunder; Yusuf Khaled Hadi; Noor Ammar Alkhuzaei; Nayla Jamal Bushaqer; Haya Isa Al Khalifa; Basma Darwish; Nawal Dayoub

doi:10.15537/smj.2025.46.4.20240555

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Figure 1
- The frequency and percentage of maternal mode of delivery by age group. Three women delivered before arrival.

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Table 1

- Demographics and maternal history of study participants.

Variables	n (%)
Maternal characteristics
Age (years)
<25	591 (19.9)
25 – 29	914 (30.8)
30 – 34	771 (25.9)
≥35	696 (23.4)
Body mass index (kg/m²)
< 35	2265 (76.2)
≥ 35	707 (23.8)
Parity
0	588 (19.8)
1	712 (24.0)
> 1	1672 (56.3)
Maternal history
Intrauterine fetal death & stillborn	91 (3.1)
Neonatal death	38 (1.3)
Previous miscarriage	783 (26.4)
Ectopic	9 (0.3)
Post-partum hemorrhage	32 (1.1)
Eclampsia & preeclampsia	34 (1.1)
Gestational diabetes mellitus	264 (8.9)
Maternal previous co-morbidities:
Anemia	180 (6.1)
Coagulopathy	13 (0.4)
Cardiac disease	17 (0.6)
Renal disorder	10 (0.3)
Autoimmune disease	10 (0.3)
Stroke	1 (0.03)
Thyroid disorder	115 (3.9)
Hyperlipidemia	9 (0.3)
Surgical history: Bariatric	47 (1.6)

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Table 2

- Maternal characteristics, comorbidities, complications, and outcomes association with maternal age.

Variables	Maternal age (years)				P-value
	<25 (n=591)	25–29 (n=914)	30–34 (n=771)	≥35 (n=696)
	n (%)	n (%)	n (%)	n (%)
Maternal characteristics
Body mass index(kg/m²)
<35	519 (87.8)	728 (79.6)	561 (72.8)	457 (65.7)	< 0.01*
≥35	72 (12.2)	186 (20.4)	210 (27.2)	239 (34.3)	< 0.01*
Conception
Spontaneous	579 (98.0)	880 (96.2)	735 (95.3)	676 (97.3)	0.118
In-vitro fertilization	10 (1.7)	28 (3.1)	32 (4.2)	18 (2.6)
Ovulation induced fertilization	2 (0.3)	6 (0.7)	4 (0.5)	1 (0.1)
Antepartum
Gestational diabetes mellitus	39 (6.6)	83 (9.1)	71 (9.2)	80 (11.5)	0.027*
Hypertension	4 (0.7)	10 (1.1)	12 (1.6)	12 (1.7)	0.320
Gestational hypertension	4 (0.7)	11 (1.2)	6 (0.8)	10 (1.4)	0.464
Eclampsia & preeclampsia	11 (1.9)	12 (1.3)	9 (1.2)	12 (1.7)	0.667
Antepartum hemorrhage
None	587 (99.3)	906 (99.1)	766 (99.4)	690 (99.1)	0.954
Placenta praevia	1 (0.2)	3 (0.3)	3 (0.4)	2 (0.3)
Abruption	3 (0.5)	5 (0.5)	2 (0.3)	4 (0.6)
Intra-partum
Premature preterm rupture of membrane	4 (0.7)	13 (1.4)	10 (1.3)	9 (1.3)	0.607
Delayed 2^nd stage of labor	7 (1.2)	9 (1.0)	6 (0.8)	4 (0.6)	0.662
Mode of delivery
Vaginal	394 (66.7)	587 (64.2)	480 (62.4)	453 (65.2)	0.418
Cesarean	197 (33.3)	327 (35.8)	289 (37.6)	242 (34.8)	0.418
Vaginal delivery estimated blood loss (ml)
<500	364 (97.6)	584 (98.5)	482 (99.4)	456 (98.5)	0.191
≥500	9 (2.4)	9 (1.5)	3 (0.6)	7 (1.5)	0.191
Cesarean delivery estimated blood loss (ml)
<1000	207 (94.5)	308 (96.0)	240 (92.3)	240 (94.1)	0.309
≥1000	12 (5.5)	13 (4.0)	20 (7.7)	15 (5.9)	0.309
Post-partum
Venous thromboembolism	0 (0.0)	1 (0.1)	1 (0.1)	0 (0.0)	0.670
Depression	2 (0.3)	5 (0.5)	2 (0.3)	2 (0.3)	0.758
Pyrexia	0 (0.0)	4 (0.4)	5 (0.6)	2 (0.3)	0.255
Wound infection & dehiscence	8 (1.4)	8 (0.9)	8 (1.0)	8 (1.1)	0.845
Hematoma	1 (0.2)	1 (0.1)	0 (0.0)	3 (0.4)	0.226
Urinary tract infection	11 (1.9)	17 (1.9)	15 (1.9)	8 (1.1)	0.625
Endometritis	0 (0.0)	1 (0.1)	1 (0.1)	0 (0.0)	0.670
Chorioamnionitis	1 (0.2)	3 (0.3)	0 (0.0)	2 (0.3)	0.463
Hysterectomy	0 (0.0)	0 (0.0)	1 (0.1)	1 (0.1)	0.559
Mortality	0 (0.0)	0 (0.0)	1 (0.1)	0 (0.0)	0.414

↵* Significant p-value <0.05, p-value was calculated using Chi-square and Fisher’s exact test as appropriate. In-vitro fertilization had one un-applicable patient, and mode of delivery had 3 un-applicable patients. Vaginal and cesarean delivery estimated blood loss, are only applicable for 1914 and 1055 patients, respectively.

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Table 3

- Fetal and Neonatal characteristics, complications, and outcomes association with maternal age.

Variables	Maternal age (Years)				P-value
	<25	25–29	30–34	≥35
	(n=591)	(n=914)	(n=771)	(n=696)
Neonatal characteristics
Gestational age
Pre-term	96 (16.2)	116 (12.7)	94 (12.2)	90 (12.9)	0.338
Term	328 (55.5)	536 (58.6)	438 (56.8)	406 (58.3)
Post-term	167 (28.3)	262 (28.7)	239 (31.0)	200 (28.7)
Birth centile
<10	36 (6.1)	58 (6.4)	52 (6.8)	37 (5.3)	0.253
10–50	169 (28.6)	253 (27.7)	251 (32.6)	197 (28.3)
51–90	240 (40.6)	383 (42.0)	317 (41.2)	297 (42.7)
>90	146 (24.7)	218 (23.9)	149 (19.4)	165 (23.7)
Delivery complications
Shoulder dystocia	0 (0.0)	1 (0.1)	1 (0.1)	1 (0.1)	0.851
Breech	22 (3.7)	19 (2.1)	23 (3.0)	24 (3.4)	0.236
Transverse	1 (0.2)	4 (0.4)	5 (0.6)	0 (0.0)	0.147
Oblique	1 (0.2)	1 (0.1)	2 (0.3)	1 (0.1)	0.898
Neonatal outcome^‡
Overall fetal complications	166 (28.1)	230 (25.2)	171 (22.2)	172 (24.7)	0.097
Miscarriage	4 (0.7)	2 (0.2)	1 (0.1)	0 (0.0)	0.075
Stillborn	4 (0.7)	3 (0.3)	7 (0.9)	5 (0.7)	0.503
Early neonatal death	4 (0.7)	1 (0.1)	5 (0.6)	1 (0.1)	0.123
Pre-term	87 (14.7)	136 (14.9)	92 (11.9)	79 (11.4)	0.087
Post-date	20 (3.4)	18 (2.0)	19 (2.5)	24 (3.4)	0.212
Large for gestational age	5 (0.8)	11 (1.2)	3 (0.4)	7 (1.0)	0.337
Small for gestational age	4 (0.7)	4 (0.4)	11 (1.4)	3 (0.4)	0.071
Intrauterine growth restriction	19 (3.2)	14 (1.5)	10 (1.3)	11 (1.6)	0.041*
Congenital anomalies	48 (8.2)	62 (6.8)	43 (5.6)	51 (7.4)	0.295

Values are presented as number and percentages (%).

Birth centile had 4 un-applicable patients.

↵* Significant p<0.05, P-value was calculated using Chi-square and Fisher’s exact test as appropriate.
↵^‡ Some women had more than one neonatal outcome.

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Table 4

- Univariate logistic regression of maternal and neonatal outcomes for maternal age:

Outcome	Maternal age (years)
	<25 (n=591)		25-29 (n=914)	30-34 (n=771)		≥35 (n=696)
	OR (95% CI)	P-value	Reference	OR (95% CI)	P-value	OR (95% CI)	P-value
Maternal outcome
GDM	0.769 (0.556 – 1.064)	0.113	Reference	0.544 (0.365 – 0.811)	0.003*	0.781 (0.557 – 1.094)	0.151
HTN	0.631 (0.271 – 1.468)	0.285	Reference	0.388 (0.125 – 1.211)	0.103	0.901 (0.402 – 2.019)	0.800
GHTN	0.836 (0.353 – 1.979)	0.683	Reference	0.467 (0.146 – 1.498)	0.201	0.538 (0.195 – 1.488)	0.232
Eclampsia and PET	0.758 (0.339 – 1.698)	0.501	Reference	1.081 (0.473 – 2.468)	0.853	0.673 (0.282 – 1.608)	0.373
PPROM	1.101 (0.468 – 2.591)	0.825	Reference	0.520 (0.159 – 1.698)	0.279	1.003 (0.405 – 2.483)	0.995
Delayed 2nd stage of labor	1.720 (0.528 – 5.610)	0.368	Reference	2.074 (0.604 – 7.119)	0.246	1.357 (0.381 – 4.828)	0.637
Mode of delivery	1.043 (0.848 – 1.282)	0.691	Reference	0.936 (0.743 – 1.180)	0.575	1.127 (0.910 – 1.395)	0.273
Fetal and neonatal outcome
Stillborn	0.455 (0.108 – 1.911)	0.282	Reference	0.942 (0.252 – 3.523)	0.929	1.266 (0.400 – 4.008)	0.688
Early neonatal death	0.761 (0.048 – 12.192)	0.847	Reference	4.736 (0.528 – 42.489)	0.165	4.537 (0.529 – 38.926)	0.168
Pre-term	1.365 (1.015 – 1.837)	0.040*	Reference	1.348 (0.973 – 1.869)	0.073	1.058 (0.769 – 1.457)	0.729
Post-date	0.563 (0.303 – 1.045)	0.069	Reference	0.981 (0.536 – 1.794)	0.950	0.707 (0.384 – 1.303)	0.267
LGA	1.199 (0.462 – 3.109)	0.709	Reference	0.840 (0.265 – 2.660)	0.767	0.384 (0.099 – 1.493)	0.167
SGA	1.015 (0.227 – 4.552)	0.984	Reference	1.574 (0.351 – 7.062)	0.554	3.343 (0.929 – 12.034)	0.065
IUGR	0.969 (0.437 – 2.147)	0.938	Reference	2.068 (0.976 – 4.383)	0.058	0.818 (0.345 – 1.939)	0.649
0.918 (0.625 – 1.349)	0.663	Reference	1.119 (0.742 – 1.687)	0.591	0.748 (0.492 – 1.137)	0.174

OR: odd ratios, CI: confidence interval, GDM: gestational diabetes mellitus, HTN: hypertension, GHTN: gestational hypertensions, PPROM: Premature rupture of membrane, LGA: large for gestational age, SGA: small for gestational age, IUGR: intrauterine growth restriction, CI: confidence interval