Group B Streptococcus (GBS, Streptococcus agalactiae) has been recognized as an important cause of perinatal morbidity and mortality. The frequency of GBS colonization ranges from 10% to 35% in... Show moreGroup B Streptococcus (GBS, Streptococcus agalactiae) has been recognized as an important cause of perinatal morbidity and mortality. The frequency of GBS colonization ranges from 10% to 35% in women of reproductive age. GBS colonization can be transient, intermittent or persistent. Vertical transmission of GBS from mother to child occurs during labor. Studies on vertical GBS transmission in colonized mothers during labor report incidences of colonization of the infant between 16 and 69%. Early-onset group B streptococcal disease (GBS-EOD) occurs in approximately 1% of newborns who are colonized with GBS. Established risk factors for acquiring GBS-EOD are prolonged rupture of membranes, preterm labor, intrapartum fever, GBS bacteriuria during pregnancy or a previous child with GBS-EOD. Intrapartum antibiotic prophylaxis (IAP) given to women at risk of transmitting GBS to their baby may prevent GBS-EOD. Identification of mothers at risk may be performed by screening (taking a culture during pregnancy to detect maternal colonization) and/ or by identifying pregnancies with one or more of the established risk factors for GBS-EOD. Since the overall effect of the Dutch guideline on the incidence of GBS-EOD is disappointing, adaptation of the Dutch guidelines should be reconsidered. The aim of this thesis is to contribute to the information needed for the establishment of an optimal prevention strategy for GBS-EOD. In this thesis, studies on prevalence of GBS carriage, risk factors for GBS-sepsis in relation to GBS carriage, timing of GBS cultures, association of GBS carriage and preterm labor and resistance of GBS for antibiotics are combined. Show less
Veneuze en arteri_le trombose zijn twee van de belangrijkste oorzaken van ziekte en sterfte in Westerse landen. Hoewel de laatste jaren is er veel bekend geworden over de oorzaken die de kans op... Show moreVeneuze en arteri_le trombose zijn twee van de belangrijkste oorzaken van ziekte en sterfte in Westerse landen. Hoewel de laatste jaren is er veel bekend geworden over de oorzaken die de kans op het krijgen van trombose verhogen, zijn er nog veel onduidelijkheden. In dit proefschrift hebben we getracht om naar aanleiding van eerder uitgevoerde genetische en observationele studies nieuwe risicofactoren voor deze twee soorten trombose op te zoeken. Tevens is de samenhang tussen arteri_le en veneuze trombose en de preventie voor trombose tijdens zwangerschap besproken. Show less
Human pregnancy is an interesting immunological paradox. The fetus is a semi-allograft, carrying paternal and maternal genes but is not rejected by the maternal immune system. The placenta is a key... Show moreHuman pregnancy is an interesting immunological paradox. The fetus is a semi-allograft, carrying paternal and maternal genes but is not rejected by the maternal immune system. The placenta is a key player in maintaining the pregnancy, since this fetus-derived organ is in direct contact with the mother. This thesis describes the results of investigations on the immune regulation at the fetal-maternal interface with emphasis on two immunological challenges during pregnancy. First, preeclampsia, which might be immunologically related to host versus graft disease as seen in solid organ transplantation and second, egg donation (ED) pregnancies, which show that even complete allogeneic fetal allografts can be tolerated by the mother. The immunological mechanisms involved in acceptance of the totally allogeneic fetus in ED pregnancies are not well understood yet. It is possible that it leads to differential immunological regulation. This hypothesis is tested in this thesis. We found differential immunological interactions in successful ED and in preeclamptic pregnancies compared with naturally conceived pregnancies. These results indicate that preeclampsia and ED pregnancies are indeed immunological challenges during pregnancy. It is a scientific challenge to further reveal the immunological mechanisms, contributing to precious information for the fields of immunology, transplantation and obstetrics. Show less
