Table 1. Characteristics of the patients at baseline and outcomes of controlled ovarian hyperstimulation.
Baseline characteristics
|
OHSS group (n=385)
|
Control group
|
Unmatched (n=6356)
|
P value
|
Matched 1:4 (n=1540)
|
P value
|
Age (years), mean ±SD
|
29.3±3.8
|
30.3±4.3
|
<0.001
|
29.4±4.0
|
0.585
|
BMI (kg/m2)
|
21.8±2.7
|
22.5±3.0
|
<0.001
|
21.8±2.7
|
0.997
|
Duration of infertility (years)
|
3.8±2.4
|
4.2±3.0
|
0.002
|
3.8±2.6
|
0.964
|
Baseline FSH (mIU/ml)
|
6.5±1.7
|
7.1±2.2
|
<0.001
|
6.5±1.8
|
0.876
|
Baseline LH (mIU/ml)
|
6.0±4.3
|
5.4±3.3
|
0.005
|
6.0±4.0
|
0.939
|
AFC
|
14.7±5.8
|
12.8±6.0
|
<0.001
|
14.5±6.4
|
0.588
|
Indications for IVF
|
|
|
|
|
|
Unexplained factors (%)
|
10 (2.6)
|
320 (5.0)
|
0.031
|
42 (2.7)
|
0.888
|
Anovulatory disorders (includes PCOS)
|
67 (17.4)
|
563 (4.9)
|
<0.001
|
216 (14.0)
|
0.094
|
Tubal factors
|
157 (40.8)
|
2923 (46.0)
|
0.046
|
670 (43.5)
|
0.334
|
Endometriosis-associated
|
7 (1.8)
|
137 (2.2)
|
0.657
|
25 (1.6)
|
0.789
|
Male factors
|
111 (28.8)
|
2060 (32.4)
|
0.144
|
449 (29.2)
|
0.900
|
Pelvic inflammatory disease
|
3 (0.8)
|
56 (0.9)
|
1
|
13 (0.8)
|
1.000
|
Multiple factors
|
33 (8.6)
|
605 (9.5)
|
0.538
|
138 (9.0)
|
0.810
|
E2 level on hCG trigger day (pg/ml)
|
4484.9±1905.8
|
4098.5±2715.2
|
<0.001
|
4521.6±4030.0
|
0.795
|
No. of oocytes retrieved
|
12.2±2.9
|
10.5±3.8
|
<0.001
|
12.2±4.0
|
0.906
|
Multiple gestations, no. (%)
|
179 (46.5)
|
1719 (27.1)
|
<0.001
|
725 (47.0)
|
0.837
|
Note: Data are expressed as n (%) unless otherwise indicated. Plus-minus values are the mean±SD; SD: Standard deviation. Statistically significant at P<0.05.
OHSS, Ovarian hyperstimulation syndrome; IVF, In vitro fertilization; AFC, Antral follicle count; FSH, Follicle-stimulating hormone; LH, Luteinizing hormone; hCG, Human chorionic gonadotropin; BMI, Body mass index (the body mass index is the weight in kilograms divided by the square of the height in meters); PCOS, Polycystic ovary syndrome (polycystic ovaries were defined as the presence of an antral follicle count of 12 or more or a volume of more than 10 cm3 in at least one ovary); Multiple factors, Infertility due to more than one infertility factor; Multiple gestations, diagnosis based on ultrasound during early pregnancy.
Table 2. The characteristics of the OHSS group patients.
Characteristic
|
Moderate group (n=83)
|
Severe-to-critical group (n=302)
|
Matched control group 1:4 (n=1540)
|
P1 value1-2
|
P2 value1-3
|
P3 value2-3
|
E2 level on hCG trigger day (pg/ml)
|
4739.0±1754.6
|
4415.2±1935.7
|
/
|
0.171
|
/
|
/
|
Hospital days (days)
|
9.3±4.7
|
13.8±7.2
|
/
|
<0.001
|
/
|
/
|
DT (days)
|
14.0+3.3
|
13.1+4.7
|
/
|
0.136
|
/
|
/
|
HCT (%)
|
42.0±4.1
|
44.9±5.7
|
/
|
<0.001
|
/
|
/
|
WBC (×109)
|
14.0±4.4
|
15.4±4.8
|
/
|
0.012
|
/
|
/
|
Albumin (g/L)
|
37.0±4.2
|
36.7±5.0
|
/
|
0.574
|
/
|
/
|
Surgical treatment, no. (%)
|
14/83 (16.9)
|
133/303 (44.0)
|
/
|
<0.001
|
/
|
/
|
Miscarriages, no. (%)
|
9/83 (10.8)
|
38/302 (12.6)
|
209/1540 (13.6)
|
0.668
|
0.478
|
0.645
|
Live birth delivery rate, no.(%)
|
74/83 (89.2)
|
264/302 (87.4)
|
1331/1540 (86.4)
|
0.668
|
0.478
|
0.645
|
Obstetric complications
|
6/83 (7.2)
|
21/302 (7.0)
|
49/1540 (3.2)
|
0.931
|
0.058
|
0.002
|
Neonatal complications
|
6/108 (5.6)
|
12/395 (3.0)
|
40/1946 (2.1)
|
0.240
|
0.031
|
0.227
|
Premature delivery
|
15/74 (20.3)
|
52/264 (19.7)
|
262/1331 (19.7)
|
0.913
|
0.902
|
0.996
|
Average neonatal weight (g)
|
2698.8±666.2
|
2828.6±563.2
|
2853.6±659.6
|
0.042
|
0.018
|
0.436
|
Singletons
|
41 /74 (55.4)
|
133/264 (44.0)
|
721/1331 (54.2)
|
0.444
|
0.835
|
0.259
|
Multiples
|
33/74 (44.6)
|
131/264 (49.6)
|
610/1331 (45.8)
|
0.444
|
0.835
|
0.259
|
Duration of gestation (weeks)
|
37.8±2.8
|
38.1±2.0
|
38.7±2.1
|
0.435
|
<0.001
|
0.001
|
LBW, no.(%)
|
30/108 (27.8)
|
98/395 (24.8)
|
528/1946 (27.1)
|
0.530
|
0.883
|
0.342
|
Note: Data are n (%) unless otherwise indicated. Plus-minus values are the mean±SD; SD: Standard deviation. Statistically significant at P<0.05.
Statistical analysis of baseline data in the above groups revealed no difference, and the results are not shown.
P1 value was Moderate group vs. Severe-to-critical group,
DT, Days after transplantation; OHSS patients were hospitalized for several days after transplantation.
HCT, Red blood cell-specific volume. Normal range of values: 37-43%; pregnant: <35%.
WBC, White blood cell count. Normal range of values: 15-22×109/l, pregnant: 6-20×109/l.
Table 3. Pregnancy and neonatal outcomes of Logistic and Propensity score matching.
Outcomes
|
OHSS group (n=385)
|
Binary logistic regression analysis Propensity score matching
|
Unmatched (n=6356)
|
P value
|
Matched 1:4 (n=1540)
|
P value
|
Live birth delivery rate, no. (%)
|
338/385 (87.8)
|
5380/6356 (84.6)
|
0.164
|
1331/1540 (86.4)
|
0.481
|
Singleton, no. (%)
|
174/338 (51.5)
|
3913/5380 (72.7)
|
<0.001
|
721/1331 (54.2)
|
0.376
|
Multiple, no. (%)
|
164/338 (48.5)
|
1467/5380 (27.3)
|
<0.001
|
610/1331 (45.8)
|
0.376
|
Preterm delivery, no. (%)
|
67/338 (19.8)
|
1456/5380 (27.1)
|
<0.001
|
262/1331 (19.7)
|
0.955
|
Miscarriages, no. (%)
|
47/385 (12.2)
|
976/6356 (15.4)
|
0.164
|
209/1540 (13.6)
|
0.481
|
Early miscarriages, no. (%)
|
23/385 (6.0)
|
607/6356 (9.6)
|
0.160
|
137/1540 (8.9)
|
0.063
|
Obstetric complications, no. (%)
|
27/385 (7.0)
|
414/6356 (6.5)
|
0.700
|
49/1540 (3.2)
|
0.001
|
PP, no. (%)
|
3/385 (0.8)
|
35/6356 (0.6)
|
0.404
|
5/1540 (0.3)
|
0.215
|
GDM, no. (%)
|
7/385 (1.8)
|
82/6356 (1.3)
|
0.178
|
9/1540 (0.6)
|
0.017
|
HDP, no. (%)
|
12/385 (3.1)
|
137/6356 (2.2)
|
0.117
|
34/1540 (2.2)
|
0.184
|
ICP, no. (%)
|
2/385 (0.5)
|
7/6356 (0.1)
|
0.056
|
1/1540 (0.1)
|
0.104
|
VT, no. (%)
|
2/385 (0.5)
|
0
|
<0.001
|
0
|
0.040
|
Duration of gestation (weeks) (mean+SD)
|
38.0±2.2
|
38.7±2.0
|
0.020
|
38.7±2.1
|
<0.001
|
Neonatal births
|
503
|
6855
|
|
1946
|
|
Neonatal complications, no. (%)
|
18/503 (3.6)
|
193/6855 (2.8)
|
0.322
|
40/1946 (2.1)
|
0.045
|
NICU, no. (%)
|
16/503 (3.2)
|
143/6855 (2.1)
|
0.103
|
33/1946 (1.7)
|
0.034
|
Congenital diseases, no. (%)
|
2/503 (0.4)
|
15/6855 (0.2)
|
0.420
|
1/1946 (0.1)
|
0.048
|
Average neonatal weight (g) (mean+SD)
|
2800.7±588.6
|
3040.0±655.3
|
<0.001
|
2853.6±659.6
|
0.081
|
LBW, no. (%)
|
128/503 (25.5)
|
1228/6855 (17.9)
|
<0.001
|
528/1946 (27.1)
|
0.441
|
Note: Data are n (%) unless otherwise indicated. Plus-minus values are the mean±SD; SD, Standard deviation. Statistically significant (P<0.05). OR, Odds ratio.
Live birth delivery rate; the number of deliveries that resulted in at least one live birth, expressed per 100 cycle attempts. the denominator in our study is the number of pregnancies who were diagnosed with clinical pregnancy after IVF/ICSI- fresh ET.
Premature delivery was defined as birth before 37 completed weeks and after 28 completed weeks of pregnancy.
Miscarriage included early- and late-term miscarriages. Early miscarriages occurred before 12 gestational weeks, and late-term miscarriages occurred between 13 and 28 gestational weeks.
Obstetric complications; PP, Placenta previa; GDM, Gestational diabetes mellitus; PROM, Premature rupture of the fetal membranes; HDP, hypertensive disorder of pregnancy,including gestational hypertension, preeclampsia, and eclampsia; ICP, Intrahepatic cholestasis of pregnancy; VT, Venous thrombosis.
Neonatal complications included prematurity, extremely low birth weight, perinatal asphyxia, major birth defects, sepsis, neonatal jaundice, and infant respiratory distress syndrome due to immaturity of the lungs.
NICU, neonatal intensive care unit, which concentrates on the care of premature babies and sick newborns, due to extreme low birth weight (LBW), perinatal asphyxia, major birth defects, sepsis, neonatal jaundice, and infant respiratory distress syndrome due to immaturity of the lungs and other complications.
Other neonatal complications: One neonatal death occurred in the NICU, and two congenital diseases occurred in the OHSS group. In the matched non-OHSS group, one death occurred within one year after birth, and one congenital disease, one chromosomal abnormality and five congenital diseases were present.
LBW, Low birth weight (birth weight <2500 g).
Threatened abortion refers to a small amount of vaginal bleeding, often dark red or bloody leukorrhea and accompanying paroxysmal abdominal pain or lower back pain in the absence of pregnancy discharge at <28 weeks of pregnancy.