Comparison of embryo quality and pregnancy outcomes for patients with low ovarian reserve in natural cycles and mildly stimulated cycles: a cohort study

Figures & data

Figure 1. Flowchart describing the selection criteria of our study cohort.

Table 1. Characteristics of total natural cycles and stimulated cycles.

	Total natural cycles	Stimulated cycles	p
Patients, n	321	343
Cycles, n	478	448
Cycles per patient, n	1.49	1.31
Age, years	37.7 ± 4.7	38.0 ± 4.8	0.370
Infertility duration, years	4.3 ± 4.1	4.6 ± 4.0	0.387
FSH, IU/L	10.94 ± 6.29	11.08 ± 6.08	0.756
LH, IU/L	5.47 ± 5.34	5.67 ± 6.06	0.626
E2, pg/mL	68.61 ± 95.24	65.46 ± 89.43	0.642
AMH, ng/mL	0.82 ± 0.90	0.78 ± 0.95	0.576
AFC, n	4.5 ± 3.3	4.7 ± 4.2	0.368
BMI, kg/m^2	21.9 ± 2.5	21.9 ± 2.6	0.934
Average total FSH dose, IU	0	1693.64 ± 897.74	<0.001
Average days of stimulation, days	0	8.8 ± 3.5	<0.001
Cancelled cycles, n (%)	0 (0)	0 (0)
Ovulation before aspiration, n (%)	28 (5.8)	0 (0)	<0.001

FSH: follicle-stimulating hormone; LH: luteinizing hormone; E₂: oestradiol; AMH: anti-Müllerian hormone; AFC: antral follicular count; BMI: body mass index.

Table 2. Laboratory and pregnancy outcomes of natural and stimulated cycles.

	Total natural cycles (n = 478)	Stimulated cycles (n = 448)	p
Cycles with no oocyte retrieved, n (%)	31 (6.5)	8 (1.8)
Cycles with oocytes, n (%)	419 (87.7)	440 (98.2)	<0.001
Oocytes retrieved, n	472	872
Mean number of oocytes, n	1.1 ± 0.5	1.9 ± 0.8	<0.001
Metaphase II oocytes, n (%)	437 (92.6)	763 (87.5)	<0.001
Utilisation rate of oocytes, %	73.3	64.6	<0.001
Fertilisation, n (%)	410 (93.8)	724 (94.9)	0.440
Normal fertilisation, n (%)	364 (83.3)	626 (82.0)	0.580
Cleavage, n (%)	358 (98.4)	621 (99.2)	0.220
Available embryos, n (%)	306 (84.1)	492 (78.6)	0.040
High-quality embryos, n (%)	225 (61.8)	333 (53.2)	0.008
Cell number of the embryos, cells	7.2 ± 2.0	7.3 ± 3.3	0.425
Blastomeres symmetry, score	1.5 ± 0.6	1.7 ± 0.7	0.001
Fragmentation, score	1.3 ± 0.6	1.4 ± 0.7	0.163
FET, n	110	202
Cancelled cycles, n (%)	0 (0)	0 (0)
No. of embryos transferred, n	1.9 ± 0.2	1.9 ± 0.2	0.942
EMT when P4 start, mm	9.9 ± 2.5	10.2 ± 2.5	0.585
Clinical pregnancy rate of FET cycle, %	51.8 (57/110)	40.1 (81/202)	0.046
Early abortion rate, %	21.1 (12/57)	19.8 (16/81)	0.852
Biochemical pregnancy rate, %	9.1 (10/110)	7.9 (16/202)	0.721

FET: frozen embryo transfer; EMT: endometrial thickness; P4: progesterone.

Figure 2. Oocyte Retrieval Time in Total Natural Cycles. The frequencies of oocyte retrieval time are shown for all natural cycles and natural cycles with good quality embryos. The columns represent the number of oocyte retrieval times.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author.