Is the birthweight of singletons born after IVF reduced by ovarian stimulation or by IVF laboratory procedures?

Singletons born after IVF are at risk of adverse pregnancy outcome, the cause of which is unknown. The present study investigated the influence of ovarian stimulation and IVF laboratory procedure on birthweight. Birthweight of singleton pregnancies resulting from IVF treatment with (n=161) and without ovarian stimulation (using a modified natural cycle (MNC) protocol; n=158), and spontaneous conceptions in subfertile patients (n=132) were compared. Mean+/-SD birthweight of singletons after conventional IVF with ovarian stimulation, MNC-IVF and natural conception were 3271+/-655, 3472+/-548 and 3527+/-582 g (P=0.001). After adjustment for biological and social confounders, the difference in birthweight between conventional IVF and MNC-IVF was reduced to 88 g and the differences between conventional IVF and MNC-IVF versus spontaneous conceptions to 123 and 23 g, respectively. The results lead to three conclusions. First, a major part of the crude differences in birthweight between the three groups is related to patient and pregnancy characteristics. Second, the IVF laboratory procedure has no influence on birthweight. Third, although a trend towards lower birthweight after ovarian stimulation was found, an adverse effect of ovarian stimulation on birthweight was not substantiated.

RheoDSC: a hyphenated technique for the simultaneous measurement of calorimetric and rheological evolutions.

A newly developed hyphenated technique is presented combining an existing rheometer and differential scanning calorimeter into a single experimental setup. Through the development of a fixation accessory for differential scanning calorimeter (DSC) crucibles and a novel rotor, the simultaneous measurement is performed inside the well-controlled thermal environment of a Tzero DSC cell. Hence, the evolution of thermal and flow properties of a material can be simultaneously measured using steady or oscillatory shear measurements and regular or modulated temperature DSC measurements. Along with the construction of a prototype, a validation of the design was performed. The technique offers interesting opportunities for the investigation of flow-induced transitions, for instance, crystallization or phase separation, and provides an asset for high-throughput screening of materials. The potential of the novel technique is demonstrated by two case studies: the chemorheology during the cure of a thermosetting epoxy-amine system and the flow-induced crystallization of syndiotactic polypropylene.