Pieternel Steures

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BACKGROUND Prediction models have been developed in reproductive medicine to help assess the chances of a treatment-(in)dependent pregnancy. Careful evaluation is needed before these models can be implemented in clinical practice. METHODS We systematically searched the literature for papers reporting prediction models in reproductive medicine for three(More)
Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism, and has been hypothesized to exert either pro- or anti-atherogenic effects, depending on its localization. Decreased plasma LPL activity is associated with the high triglyceride (TG);-low HDL phenotype that is often observed in patients with premature vascular disease. In contrast, in the(More)
BACKGROUND Intrauterine insemination with controlled ovarian hyperstimulation is commonly used as first-line treatment for couples with unexplained subfertility. Since such treatment increases the risk of multiple pregnancy, a couple's chances of achieving an ongoing pregnancy without it should be considered to identify those most likely to benefit from(More)
OBJECTIVE To determine the precise degree of variability that is represented by the reproducibility and reliability of semen analysis. The general assumption is that semen analyses need to be repeated because of a high degree of within-individual variability. However, the precise degree of variability is not well established in male partners of subfertile(More)
BACKGROUND Standardization of the semen analysis may improve reproducibility. We assessed variability between laboratories in semen analyses and evaluated whether a transformation using Z scores and regression statistics was able to reduce this variability. MATERIALS AND METHODS We performed a retrospective cohort study. We calculated between-laboratory(More)
STUDY QUESTION Do two semen analyses predict natural conception better than a single semen analysis and will adding the results of repeated semen analyses to a prediction model for natural pregnancy improve predictions? SUMMARY ANSWER A second semen analysis does not add helpful information for predicting natural conception compared with using the results(More)
OBJECTIVE To evaluate the capacity of the postcoital test (PCT) to predict spontaneous pregnancy in a large cohort study of subfertile couples. DESIGN Prospective study. SETTING Department of reproductive medicine of 38 hospitals in the Netherlands. PATIENT(S) Between January 2002 and February 2004, we prospectively included consecutive subfertile(More)
OBJECTIVE To investigate the predictive capacity of immunoglobulin G ASA (direct MAR test) for spontaneous ongoing pregnancy in subfertile couples. DESIGN Prospective cohort study. SETTING Nine fertility centers in The Netherlands. PATIENT(S) Consecutive ovulatory subfertile couples. INTERVENTION(S) A basic fertility workup, including a mixed(More)
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