Physiologic changes in pregnancy

A simplified PBPK modeling approach for prediction of pharmacokinetics of four primarily renally excreted and CYP3A metabolized compounds during pregnancy

During pregnancy, a drug's pharmacokinetics may be altered and hence anticipation of potential systemic exposure changes is highly desirable. Physiologically based pharmacokinetics (PBPK) models have recently been used to influence clinical trial design or to facilitate regulatory interactions. Ideally, whole-body PBPK models can be used to predict a drug's systemic exposure in pregnant women based on major physiological changes which can impact drug clearance (i.e., in the kidney and liver) and distribution (i.e., adipose and fetoplacental unit). We described a simple and readily implementable multitissue/organ whole-body PBPK model with key pregnancy-related physiological parameters to characterize the PK of reference drugs (metformin, digoxin, midazolam, and emtricitabine) in pregnant women compared with the PK in nonpregnant or postpartum (PP) women. Physiological data related to changes in maternal body weight, tissue volume, cardiac output, renal function, blood flows, and cytochrome P450 activity were collected from the literature and incorporated into the structural PBPK model that describes HV or PP women PK data. Subsequently, the changes in exposure (area under the curve (AUC) and maximum concentration (C max)) in pregnant women were simulated. Model-simulated PK profiles were overall in agreement with observed data. The prediction fold error for C max and AUC ratio (pregnant vs. nonpregnant) was less than 1.3-fold, indicating that the pregnant PBPK model is useful. The utilization of this simplified model in drug development may aid in designing clinical studies to identify potential exposure changes in pregnant women a priori for compounds which are mainly eliminated renally or metabolized by CYP3A4.

Contemporary multidisciplinary treatment of pregnancy-associated breast cancer

Breast cancer diagnosed during pregnancy poses unique challenges. Application of standard treatment algorithms is limited by lack of level I evidence from randomized trials. This study describes contemporary multidisciplinary treatment of pregnancy-associated breast cancer (PABC) in an academic setting and explores early maternal and fetal outcomes. A search of the Dana-Farber/Harvard Cancer Center clinical databases was performed to identify PABC cases. Sociodemographic, disease, pregnancy, and treatment information, as well as data on short-term maternal and fetal outcomes, were collected through retrospective chart review. 74 patients were identified, the majority with early-stage breast cancer. Most (73.5%) underwent surgical resection during pregnancy, including 40% with sentinel lymph node biopsy and 32% with immediate reconstruction. A total of 36 patients received anthracycline-based chemotherapy during pregnancy; of those, almost 20% were on a dose-dense schedule and 8.3% also received paclitaxel. 68 patients delivered liveborn infants; over half were delivered preterm (< 37 weeks), most scheduled to allow further maternal cancer therapy. For the infants with available data, all had normal Apgar scores and over 90% had birth weight >10^th percentile. The rate of fetal malformations (4.4%) was not different than expected population rate. Within a multidisciplinary academic setting, PABC treatment followed contemporary algorithms without apparent increase in maternal or fetal adverse outcomes. A considerable number of preterm deliveries were observed, the majority planned to facilitate cancer therapy. Continued attention to maternal and fetal outcomes after PABC is required to determine the benefit of this delivery strategy.

Baby on board: what you need to know about pregnancy in the hemoglobinopathies

Pregnancy poses a unique challenge to patients with sickle cell disease and β-thalassemia, who often have exacerbations of hemolysis or anemia during the gestational period, experience higher rates of obstetric and fetal complications, and may have distinct underlying comorbidities related to vasculopathy and iron overload that can endanger maternal health. Optimal management of pregnant women with hemoglobinopathies requires both an understanding of the physiologic demands of pregnancy and the pathophysiology of disease-specific complications of inherited blood disorders. A multidisciplinary team of expert hematologists and high-risk obstetricians is therefore essential to ensuring appropriate antenatal maternal screening, adequate fetal surveillance, and early recognition of complications. Fortunately, with integrated and targeted care, most women with sickle cell disease and β-thalassemia can achieve successful pregnancy outcomes.

Maternal adaptations and inheritance in the transgenerational programming of adult disease

Adverse exposures in utero have long been linked with an increased susceptibility to adult cardio-renal and metabolic diseases. Clear gender differences exist, whereby growth-restricted females, although exhibiting some phenotypic modifications, are often protected from overt disease outcomes. One of the greatest physiological challenges facing the female gender, however, is that of pregnancy; yet little research has focused on the outcomes associated with this, as a potential 'second-hit' for those who were small at birth. We review the limited evidence suggesting that pregnancy may unmask cardio-renal and metabolic disease states and the consequences for long-term maternal health in females who were born small. Additionally, a growing area of research in this programming field is in the transgenerational transmission of low birth weight and disease susceptibility. Pathways for transmission might include an abnormal adaptation to pregnancy by the growth-restricted mother and/or inheritance via the parental germline. Strategies to optimise the pregnancy environment and/or prevent the consequences of inheritance of programmed deficits and dysfunction are of critical importance for future generations.

Cardio-renal and metabolic adaptations during pregnancy in female rats born small: implications for maternal health and second generation fetal growth

Intrauterine growth restriction caused by uteroplacental insufficiency increases risk of cardiovascular and metabolic disease in offspring. Cardio-renal and metabolic responses to pregnancy are critical determinants of immediate and long-term maternal health. However, no studies to date have investigated the renal and metabolic adaptations in growth restricted offspring when they in turn become pregnant. We hypothesised that the physiological challenge of pregnancy in growth restricted females exacerbates disease outcome and compromises next generation fetal growth. Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (Restricted) or sham surgery (Control) on day 18 of gestation in WKY rats and F1 female offspring birth and postnatal body weights were recorded. F1 Control and Restricted females were mated at 4 months and blood pressure, renal and metabolic parameters were measured in late pregnancy and F2 fetal and placental weights recorded. Age-matched non-pregnant Control and Restricted F1 females were also studied. F1 Restricted females were born 10-15% lighter than Controls. Basal insulin secretion and pancreatic β-cell mass were reduced in non-pregnant Restricted females but restored in pregnancy. Pregnant Restricted females, however, showed impaired glucose tolerance and compensatory glomerular hypertrophy, with a nephron deficit but normal renal function and blood pressure. F2 fetuses from Restricted mothers exposed to physiological measures during pregnancy were lighter than Controls highlighting additive adverse effects when mothers born small experience stress during pregnancy. Female rats born small exhibit mostly normal cardio-renal adaptations but altered glucose control during late pregnancy making them vulnerable to lifestyle challenges.

Clinical therapeutics in pregnancy

Most drugs are not tested for use during pregnancy, consequently, labeling, which may include information about fetal safety, includes nothing about dosing, efficacy, or maternal safety. Yet these are concerns of health care providers considering treatment of disease during pregnancy. Therefore, the practitioner treats the pregnant woman with the same dose recommended for use in adults (typically men) or may decide not to treat the disease at all. However, is the choice of not treating a woman during pregnancy better than dealing with the challenges which accompany treatment? This paper, which summarizes metabolic and physiologic changes induced by pregnancy, illustrates that standard adult dosing is likely to be incorrect during pregnancy.

Renin angiotensin signaling in normal pregnancy and preeclampsia

Many reports indicate that there is an increase in almost all of the components of the renin-angiotensin system (RAS) during an uncomplicated pregnancy, but renin activity, angiotensin II, and aldosterone decrease in preeclampsia (PE) for reasons that are unclear. PE is a life-threatening disorder of late pregnancy characterized by hypertension, proteinuria, increased soluble fms-like tyrosine kinase-1, as well as renal and placental morphologic abnormalities. Although a leading cause of maternal and perinatal morbidity and mortality, the pathogenic mechanisms of PE remain largely undefined. Immunologic mechanisms and aberrations of the RAS have been long considered contributors to the disorder. Bridging these two concepts, numerous studies report the presence of the angiotensin II type I receptor agonistic autoantibody (AT(1)-AA) found circulating in preeclamptic women. This autoantibody induces many key features of the disorder through AT(1) receptor signaling, and has been implicated in the pathogenesis of PE. Here we review the functions of the RAS during normal pregnancy and PE, and highlight the role of AT(1)-AA in both animal models and in the human disorder.

Comparison of hemodynamic, biochemical and hematological parameters of healthy pregnant women in the third trimester of pregnancy and the active labor phase

BACKGROUND

Pregnancy is accompanied by several hemodynamic, biochemical and hematological changes which revert to normal values after labor. The mean values of these parameters have been reported for developed countries, but not for Mexican women. Furthermore, labor constitutes a stress situation, in which these factors may be altered. It is known that serologic increase of heat shock protein (Hsp) 70 is associated with abnormal pregnancies, presenting very low level in normal pregnant women. Nevertheless, there are no studies where these measurements are compared in healthy pregnant women at their third trimester of pregnancy (3TP) and the active labor phase (ActLP).

METHODS

Seventy five healthy Mexican pregnant women were included. Hemodynamic, biochemical and hematological parameters were obtained in all cases, and serum Hsp70 levels were measured in a sample of 15 women at 3TP and at ActLP.

RESULTS

Significant differences were found in most analysis performed and in Hsp70 concentration at 3TP as compared to ActLP, however all were within normal range in both conditions, supporting that only in pathological pregnancies Hsp70 is drastically increased.

CONCLUSION

Results obtained indicate that 3TP and ActLP have clinical similarities in normal pregnancies, therefore if abnormalities are found during 3TP, precautions should be taken before ActLP.

Pulmonary physiology in pregnancy

This section reviews anatomic and functional changes of the respiratory system during pregnancy. Pulmonary function during exercise in pregnancy and in the obese gravida, sleep-disordered breathing during pregnancy, and pulmonary changes in the pregnant woman living at altitude are discussed in detail. Assessment of pulmonary function and interpretation of the arterial blood gas during pregnancy are also discussed.

Pharmacotherapy and pregnancy: highlights from the Second International Conference for Individualized Pharmacotherapy in Pregnancy

To address provider struggles to provide evidence-based, rational drug therapy to pregnant women, a second conference was convened to highlight the current research in the field. Speakers from academic centers and institutions spoke about: the unique physiology and pathology of pregnancy; pharmacokinetic changes in pregnancy; thyroid disorders in pregnancy; pharmacogenetics in pregnancy; the role of CYP2D6 in pregnancy; treating addiction in pregnancy; the power of teratology networks to inform clinical decisions; the use of anti-depressants in pregnancy; and how to utilize computer-based modeling to aid with individualized pharmacotherapy in pregnancy. The Conference highlighted several areas of collaboration with the current Obstetrics Pharmacology Research Units Network (OPRU) and hoped to stimulate further collaboration and knowledge in the area with the common goal to improve the ability to safely and effectively use individualized pharmacotherapy in pregnancy.

Urologic emergencies in pregnancy

The management of urological emergencies during pregnancy presents unique clinical challenges for the treating physician. Clinical signs and symptoms are often subtle while diagnostic and therapeutic options are limited in treating patients to avoid fetal morbidity. A high index of suspicion with early diagnosis and treatment are essential for the management of genitourologic emergencies in pregnant women. It is essential for patients to be managed on an individual basis using a multidisciplinary approach.

Repeated episodes of respiratory distress in an obese parturient after cesarean delivery

A 25-yr-old obese parturient with mild asthma underwent an uneventful spinal anesthetic for primary cesarean delivery. Within 4 h after delivery, the patient twice developed acute shortness of breath, inspiratory stridor, and hypoxemia that required intubation. A battery of blood tests revealed no evidence of an allergic reaction. She had a normal echocardiogram and chest computed tomography, but her neck computed tomography showed an enlarged left thyroid lobe asymmetrically compressing the endotracheal tube cuff. We hypothesized that, after delivery, decreased maternal vascular capacitance increased central venous pressure such that venous engorgement of an undiagnosed goiter may have caused symptomatic tracheal compression.