Eastern Finland Laboratory Centre and Institute of Clinical Medicine, Faculty of Medicine, University of Kuopio, P.O. Box 1700, 70211 Kuopio, Finland.
Hum Reprod. 2010 Feb;25(2):412-7. doi: 10.1093/humrep/dep417. Epub 2009 Nov 26.
Time-to-pregnancy (TTP) is a clinical tool used to measure uterine receptivity and a couples' fertility in spontaneously conceived pregnancies. The objective of this study was to examine the effects of TTP on first trimester Down's syndrome (DS) markers in spontaneous, chromosomally normal pregnancies and to compare the results to those in IVF pregnancies.
A case-control study was conducted amongst patients attending a university hospital in Finland. During 2005-2007 data on pregnant women in Kuopio, with singleton pregnancies, routinely collected by the Department of Obstetrics and Gynaecology of Kuopio University Hospital and Eastern Finland Laboratory Centre were compiled. The data comprised information gathered in first trimester DS screening [age of the mother, serum hCG free beta subunit (fbeta-hCG) and pregnancy-associated plasma protein A (S-PAPP-A) levels and the nuchal translucency (NT) of the fetus], body mass index, method of conception [spontaneous or in vitro fertilization (IVF)], TTP (in spontaneous pregnancies), maternal chronic diseases, smoking habits of the mother, outcome of the pregnancy and prior pregnancy complications. Spontaneous pregnancies were classified into three groups by TTP: 0-12 months (the reference group, N = 1164), 13-24 months (N = 112) and > or = 25 months (N = 70). Screening data from IVF pregnancies (N = 39) were collected for comparison. The size of the total study population was 1385.
The median/geometric mean multiple of median (MOM) of S-PAPP-A was significantly lower (P < 0.01) in women with a TTP over 25 months (0.89/0.83 MOM) and in the IVF group (0.95/0.84 MOM) compared with the reference group (1.01/1.03 MOM). However, first trimester S-fbeta-hCG and NT MOMs were not statistically different between the study groups. Consequently, the proportion of DS screening positives was significantly higher in women with TTP > or = 25 months (12.9 versus 2.1%), but not in the IVF group (2.6%).
A TTP of over 2 years altered the levels of DS screening serum markers to levels similar to those observed in IVF pregnancies, with a decrease in PAPP-A levels compared with the reference group. These results raise the possibility that such changes could be related to subfertility rather than to the use of assisted reproductive technology.
妊娠时间（TTP）是一种用于衡量子宫接受性和自然受孕夫妇生育能力的临床工具。本研究的目的是检测 TTP 对自然受孕、染色体正常妊娠的第一孕期唐氏综合征（DS）标志物的影响，并将结果与体外受精（IVF）妊娠进行比较。
这是一项在芬兰一所大学医院进行的病例对照研究。2005-2007 年，收集了由库奥皮奥大学医院妇产科和东芬兰实验室中心常规收集的、在库奥皮奥就诊的单胎妊娠孕妇的数据。数据包括在第一孕期 DS 筛查中收集的信息[母亲年龄、血清人绒毛膜促性腺激素游离β亚基（hCG free beta subunit，fβ-hCG）和妊娠相关血浆蛋白 A（pregnancy-associated plasma protein A，S-PAPP-A）水平以及胎儿颈项透明层（nuchal translucency，NT）]、体重指数、受孕方式[自然或体外受精（IVF）]、TTP（在自然受孕妊娠中）、母亲慢性疾病、母亲吸烟习惯、妊娠结局和既往妊娠并发症。将自然受孕妊娠根据 TTP 分为三组：0-12 个月（参考组，N=1164）、13-24 个月（N=112）和>或=25 个月（N=70）。收集 IVF 妊娠（N=39）的筛查数据进行比较。总研究人群的大小为 1385 人。
TTP 超过 25 个月（0.89/0.83 MOM）和 IVF 组（0.95/0.84 MOM）的 S-PAPP-A 中位数/几何均数倍数（MOM）明显低于参考组（1.01/1.03 MOM）（P<0.01）。然而，各组间第一孕期 S-fβ-hCG 和 NT MOM 无统计学差异。因此，TTP>或=25 个月的孕妇 DS 筛查阳性率明显较高（12.9%比 2.1%），而 IVF 组则不然（2.6%）。
TTP 超过 2 年可使 DS 筛查血清标志物水平发生变化，与 IVF 妊娠相似，与参考组相比，PAPP-A 水平降低。这些结果提示这些变化可能与生育能力低下有关，而与辅助生殖技术的应用无关。
