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Pregnancy Timeline by SemestersThird TrimesterInner Ear Bones HardenFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
CLICK ON weeks 0 - 40 and follow along every 2 weeks of fetal development
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Home | Pregnancy Timeline | News Alerts |News Archive Jan 15, 2015

Research shows quitting smoking could be easier for women during the mid-luteal phrase of menustration (10 - 14), or after ovulation when levels of estrogen and progesterone are high.
Image Credit: Encyclopedia Britannica Kids


Inner Ear Bones Harden



Quitting smoking? Women time it to your cycle!

Neuroscience reveals that women crave cigarettes more during their menstrual periods. Coordinating quiting smoking with the timing of your period might help.

The menstrual cycle appears to have an effect on nicotine cravings, according to a new study from the University of Montreal by Adrianna Mendrek and its affiliated Institut universitaire en santé mentale de Montréal.

"Our data reveals that urges to smoke are stronger at the beginning of the follicular phase that begins after menstruation. Hormonal decrease of estrogen and progesterone possibly deepen withdrawal and increase activity of neural circuits associated with cravings."

Adrianna  Mendrek PhD, University of Montreal and Institut universitaire en santé mentale de Montréal.

Mendrek believes it could be easier for women to overcome withdrawal symptoms during the mid-luteal phrase of menustration, or after ovulation when levels of estrogen and progesterone are high. The findings were published in Psychiatry Journal.

Researchers came to this conclusion after working with 34 men and women who each smoke more than 15 cigarettes a day. Smokers filled out questionnaires and underwent MRI brain scans taken while they looked at either neutral pictures or pictures making smoking look attractive. Women were scanned twice - once at the beginning of the follicular phase of their menstrual cycle and again at the mid-luteal phase. Estrogen and progesterone levels were also measured.

One in ten smokers may manage to stop smoking within one year. Women smokers have even less success than men quitting, even when they smoke the same amount.

  In rodent drug studies of nicotine, scientists have observed gender affects addiction response. "Female rats become addicted more quickly, and are willing to work harder for the same dose," Mendrek explained. This observation led Mendrek's team to conclude that females are perhaps at a higher risk of addiction, and therefore their hormones could be the reason.

The situation is more difficult to unravel in humans as each smoker is unique in terms of tobacco use, personal history, personality, social situation and environment. Mendrek adds: "Stress, anxiety and depression are probably the more important factors to take into consideration. Having said that, amongst young people, tobacco use by women is increasing."

So researchers led their study with two specific objectives: first to check for gender differences in neural circuits linked to craving; second to determine if electrocortical changes, associated with nicotine withdrawal, fluctuate in synch with female hormone variations.

No significant differences were found between men and women with regards to neural circuits. But, female neural patterns varied considerably over their menstrual cycle.

Certain areas of women's frontal, temporal and parietal cortex revealed greater activation during their follicular phase, while limited activation was recorded in their hippocampus during the luteal phase.

Mendrek hopes her conclusions will encourage researchers to pay greater attention to biology when designing their research protocols. "A greater knowledge of the neurobiological mechanisms governing addiction should enable us to better target treatment according to the smokers profile," she said.

While overall more men than women smoke cigarettes, women and girls take less time to become dependent after initial use and have more difficulties quitting the habit. One of the factors contributing to these differences may be that women crave cigarettes more than men and that their desire to smoke is influenced by hormonal fluctuations across the menstrual cycle. Therefore, the purpose of the present study was twofold: (a) to examine potential sex/gender differences in functional neuroanatomy of craving and to (b) delineate neural correlates of cigarette cravings in women across their menstrual cycle. Fifteen tobacco-smoking men and 19 women underwent a functional MRI during presentation of neutral and smoking-related images, known to elicit craving. Women were tested twice: once during early follicular phase and once during midluteal phase of their menstrual cycle. The analysis did not reveal any significant sex differences in the cerebral activations associated with craving. Nevertheless, the pattern of activations in women varied across their menstrual cycle with significant activations in parts of the frontal, temporal, and parietal lobe, during follicular phase, and only limited activations in the right hippocampus during the luteal phase.

About this study: Professor Adrianna Mendrek is affiliated with the Department of Psychiatry at the University of Montreal and the Research Centre at the Institut universitaire en santé mentale de Montréal. Her department and centre colleagues, Professor Stéphane Potvin, Josiane Bourque, Laurence Dinh-Williams, contributed to the findings. They published "Sex Differences and Menstrual Cycle Phase-Dependent Modulation of Craving for Cigarette: An fMRI Pilot Study" in Psychiatry Journal on October 27, 2014. The research received funding from the Fonds de Recherche du Québec - Santé.

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